Chery Fora A21 2007 User Manual

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

CONTENT

1. NOTICE TO THEEFI SYSTEMSERVICE.........................................................................................3

1.1. GENERALSERVICE...........................................................................................................................3

1.2. NOTICE DURING THE SERVICE.............................................................................................3

1.3. SERVICETOOLS .........................................................................................................................4

1.4. EXPLANATIONS OFTHE ABBREVIATION IN THE MANUAL.........................................7

2. ME7.9.7 SYSTEM INTRODUCTION....................................................................................................7

2.1. SYSTEM BASIC PRINCIPLE.....................................................................................................7

2.1.1 SYSTEM GENERALINTRODUCTION: ME7.9.7-MOTRONIC EMS .......................7

2.2. CONTROLSIGNAL: ME7.9.7 SYSTEM INPUT/OUTPUT SIGNAL....................................9

2.3. INTRODUCTION OFSYSTEM MALFUNCTION DIAGNOSIS FUNCTION...................10

2.3.1. MALFUNCTION INFORMATION RECORD .............................................................10

2.3.2, CONTROLSTRATEGYOF FAILURE LAMP ............................................................10

2.3.3, DIAGNOSIS METER CONNECTION..........................................................................11

2.3.4, READ MALFUNCTION INFORMATION BY WINK CODE....................................11

3. WORKING PRINCIPLEAND CHARACTER OF EFI SYSTEM ELEMENT...............................11

3.1 ELECTRONIC CONTROLUNIT - ECU..................................................................................11

3.2 COOLANT TEMPERATURE SENSOR....................................................................................15

3.3 KNOCK SENSOR ........................................................................................................................16

3.4 OXYGEN SENSOR......................................................................................................................17

3.5 SPEED SENSOR (CRANKCASE POSITIONING SENSOR).................................................18

3.6 PHASE SENSOR (CAM SHAFT POSITIONING SENSOR)..................................................20

3.7 ELECTRIC FUELPUMP............................................................................................................21

3.8 ELECTROMAGNETIC INJECTOR.........................................................................................22

3.9 AIR FLOWSENSOR ...................................................................................................................23

3.10 DOUBLE SPARK IGNITION COIL........................................................................................24

3.11CARBON CANISTER SOLENOID VALVE............................................................................26

3.12 FUELPRESSURE REGULATOR............................................................................................27

3.13 ELECTRONIC THROTTLEVALVEAND ACCELERATOR..............................................28

3.14 FAN CONTROL.........................................................................................................................29

3.15AIR CONDITIONER CONTROL............................................................................................30

4 ME7 SYSTEM TESTAND REPAIR ACCORDING TO TDC ...........................................................31

4.1 ENGINE DTC (DIAGNOSTIC TROUBLE CODE) LIST.......................................................32

4.2 DIAGNOSIS FLOWWHEN THERE IS DIFFERENT DTC...................................................33

5. TYPICALFAILUREAND ITS DIAGNOSIS FLOW.........................................................................56

5.1 EXPLANATION ...........................................................................................................................56

5.2 TYPICALFAILUREDIAGNOSIS FLOW................................................................................57

1. The engine does not rotate or rotate slowlywhen it is started ............................................57

2. The engine can draw rotating but can not start successfully when it is started................58

3. It is hard to start the heating car...........................................................................................59

4. It’s hard to start the cold car..................................................................................................60

5. Normal engine speed but hard to start at any time..............................................................61

6. Regular starts but the idle speed is not steady at any time..................................................62

7. Regular starts but the idle speed is not steady during engine heating. ..............................63

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

8. Regular starts but idle speed is not steady after the engine heating...................................64

9. Regular starts but idle speed is not steady or dying out when there is partial loading.....65

10. Regular starts with high idle speed......................................................................................66

11. Low engine speed ordying out exists when it is accelerated.............................................67

12. React slowly when it is accelerated......................................................................................68

13. The performance is poor when it is accelerated.................................................................69

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

EFI SERVICE MANUAL

A21 car is equipped with ME7.9.7 EFI system which developed by UAES. This manual will introduce the general service and the operational principle and character of sensor elements of EFI system in detail. At last there will be some diagnostic method and flow for the typical problems.

1. NOTICE TO THE EFI SYSTEM SERVICE

1.1. GENERAL SERVICE

● Digital multimeter is the only permitted instrument to inspect the EFI system.

● Please use the quality spare parts for service, otherwise can not make sure the EFI work

properly.

● Please use lead free gasoline during service.

● Please be obedient to the service and diagnose flow.

● It is forbidden to disassembly the EFI part during service.

● It should be careful to take the electronic component (ECU, sensor, etc.) for preventing

from dropping to the ground.

● Please protect the environment, deal with the rejectamenta carefully and effectively.

1.2. NOTICE DURING THE SERVICE

● Do not disassemble any part or inserts of the EFI system from its original position at

random to prevent from damaging parts or that moisture and dirt oil come into the inserts. And that will keep the system from working properly.

● Please leave the ignition switch at shut off position when you disconnect and connect the

inserts otherwise it will damage the electric element.

● It is must keep the ECU under 80★, when you do the work of hot status simulation and

other works which may cause the temperature increase.

● The supplying oil pressure is high(around 300kPa), all the fuel pipe is made up of anti

high pressure pipe. There is high pressure in fuel pipe even the engine does not run. So do

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

not disassemble the fuel pump at random when carrying out service for fuel system. Before disassemble the fuel pipe please carry out discharge pressure procedure. The method is as below: Disassemble the fuel pump relay (or disconnect the connector plug), start engine at its idle running and it dies out by itself. After the service supply fuel to engine fuel pipe at first, the method is: turn ignition key to ON position and wait a while, repeat this four or five times. Disassembly of fuel pipe and fuel filter should be carried out at a place with good ventilation and done by professional maintainer.

● Do not give electricity to fuel pump when the electrical pump is taken out of fuel tank in

order to prevent from electrical spark and cause fire.

● Fuel pump is not allowed to carry out running test at dry or water situation, which will

decrease its life. And do not exchange anode and cathode of the pump.

● Carry out jump spark inspection at necessary time when inspect the ignition system, and

the time to inspect must be short. Do not open the throttle valve to prevent a lot of unburned gasoline entering exhaust pipe and damage the 3-way catalytic converter ( It is better to take off the corresponding injector insert during the jump spark testing)

● The adjustment of idle speed is done completely by EFI without manual work. The

accelerator stop screw of throttle valve has been fixed well in advance by manufacturer so that it is not allowed to change it original position by the customer.

● Do not exchange the anode and cathode of the accumulator to prevent damaging the

electronic component. This system uses cathode ground.

● Do not disassemble accumulator cable when the engine is running.

● Disassemble the cable of accumulator anode and cathode, and ECU when there is welding

work on the car.

● Do not inspect the input and output signal of component by impaling the lead surface.

1.3. SERVICE TOOLS

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Tool name:

EFI system diagnostic tester

Function:

Read/clear the breakdown code in EFI and inspect data, test part motion.

Tool name:

Ignition timing lamp

Function:

Inspect engine ignition timing.

Tool name:

Digital multimeter

Function:

Inspect the character parameter of voltage, current, resistance.

Tool name:

Fuel pressure gauge

Function:

Inspect the pressure in fuel system, judge the status of fuel pump and fuel pressure regulator.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Tool name:

Pressure gauge for cylinder

Function:

Inspect the pressure in every cylinder.

Tool name:

Fuel injector cleaner and analyzer

function:

Analyze and clean the injector.

Tool name:

Vacuum meter

function:

Inspect the pressure of intake manifold

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

1.4. EXPLANATIONS OF THEABBREVIATION IN THE MANUAL

DG Speed Sensor DVE Electronic Throttle Valve DR Fuel Pressure Regulator FPM Accelerator Pedal ECU Electronic Control Unit (Computer) EKP Fuel Pump EMS Engine Management System EV Fuel Injector LSH Heating Oxygen Sensor KS Knock Sensor KSZ Fuel Distributing Pipe Assembly KVS Fuel Distributing Pipe ROV Ignition System with Distributor PG Phase Sensor RUV Ignition System without Distributor TEE Oil Pump Bracket Assembly TF-W Coolant Temperature Sensor TEV Purge Canister Control Valve HFM Air Flow Sensor ZSK Ignition Coil

2. ME7.9.7 SYSTEM INTRODUCTION

2.1. SYSTEM BASIC PRINCIPLE

2.1.1 SYSTEM GENERAL INTRODUCTION: ME7.9.7-MOTRONIC EMS

Engine management system (EMS)is composed mainly by three components: sensor, ECU, and actuator. And these three parts control the intake air quantity, fuel injection quantity and ignition advance angle. The basic frame is shown in chart 2.1.

Diagnose

Sensor ECU Actuator

Engine

Diagnose

Chart 2.1 compose of engine electronic control system

In engine electronic control system, the sensor is the input part used for measuring all kinds of physics signal (temperature and pressure etc.) and change them to corresponding electronic signal; the function of ECU is accepting the signal and calculate it according to the programmed program and generate corresponding output signal to power drive circuit; and the power drive circuit makes the engine running according to established strategy by driving every actuator to do different action; at the same time the malfunction diagnosis system of ECU monitors all parts or control function, and if a malfunction is detected and confirmed it will memorize malfunction code, transferring “ limping home” function, and when the malfunction is deleted, the normal value will be desterilized.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Engine electronic control system schematic of ME7.9.7 chart 2.2

Phase Sensor

Ignition Coil

Canister Control Valve

Trouble Light DiagnosisAccess

Anti Theft

ElectronicAccelerator Onboard Diagnosis (Europe) Returnless Fuel Supply System

Air intake temperature sensor

Throttle Valve

Accelerator Pedal

Fuel Distribution PipeAssembly

Knock Sensor

Speed Sensor

Electric Fuel Pump

Temperature Sensor

UAES Parts

Phase Sensor

Oxygen Sensor

Front Catalytic Converter

Oxygen Sensor

Main Catalytic Converter

Chart 2.2

The basic component of ME7.9.7 engine electronic control system:

Electronic Control Unit(ECU) Accelerator Electronic Throttle Valve Air Quality Flow Meter Injector Electronic Fuel Pump Coolant temperature sensor Fuel Pressure Regulator Throttle position sensor Fuel Pump Bracket Camshaft Position Sensor Fuel Distributing Pipe Speed Sensor Oxygen Sensor Canister Control Valve Knock Sensor Ignition Coil

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

ME7.9.7 engine management system is an electronic gasoline control system, and it can provide lots of control characters about operator and vehicle or equipment. The system adopts a combination method of open loop and closed loop (feed back) control to provide all kinds of control signal to engine. The main function of the system:

1) The basic functions of applying physics mode engine  For the system structure based on torque, the airflow sensor will confirm the loading

of cylinder and improve the mixture air control function closed loop control.

 Fuel injects ignition timing on the order of cylinder order, including knock control

and emission control functions.

 3 way catalytic convert heating  Canister control  Idle speed control  Limping home

2.2. CONTROL SIGNAL: ME7.9.7 SYSTEM INPUT/OUTPUT SIGNAL

The main sensor input signal of ECU of ME7 system:

 Air flow signal  Throttle valve corner signal  Coolant temperature signal  Engine speed signal  Phase signal  Knock sensor signal  Oxygen sensor signal  Speed signal  Air conditioner pressure signal

The above information after the transaction of ECU, there will generate required actuator control signal, and this signal will be magnified in output driving circuit and was transferred to its corresponding actuator. The signals include below information:

 Injection timing and injection continuous time  Fuel pump relay  Opening degree of canister control valve  Ignition coil closing angle and ignition angle of advance  Air conditioner compressor relay

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

 Cooling fan relay

2.3. INTRODUCTION OF SYSTEM MALFUNCTION DIAGNOSIS FUNCTION

2.3.1. MALFUNCTION INFORMATION RECORD

The ECU monitors sensor, actuator, related circuit, malfunction indicator and accumulator voltage etc., and EUC itself continuously. At the same time the ECU inspect the reliability test on sensor signal output, actuator driving signal and internal signal (e.g.: closed loop control, coolant temperature, knock control, idle engine speed and accumulator voltage etc.). ECU will set the malfunction record on RAM malfunction memory immediately once the malfunction or the unlikelihood signal is detected. The malfunction information is recorded by malfunction code and displayed according to its appeared order, dividing malfunction into “steady malfunction”and “contingency malfunction”(for example the malfunction is caused by short time cable braking or bad contact of the inserts) according to its appeared frequency.

Function Diagnosis Function Diagnosis

ECU

Data Collection

Sensor

Engine

Control Order

Actuator

Chart 2.4 EFI System Malfunction Diagnosis Principle Chart

2.3.2, CONTROL STRATEGYOFFAILURE LAMP

When there is no trouble:

★ The failure lamp is lighting and die out within 4 seconds after the ignition switch is ON ★ Starting within 4 seconds, the failure lamp dies when the engine speed signal is found; ★ The failure lamp winking at 2HZ frequency when the K cable contact to ground more

than 2.5 seconds.

When there is a trouble:

★ The failure lamp always on light when the ignition switch is ON; ★ Start and die out when the engine speed signal is detected; if the failure lamp was defined

as lighting mode, it will always on light after reach its confirmed conditions;

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

★ Output winking code that is P-CODE value after the K cable contact with the ground

more than 2.5 seconds. For example: the winking mode of P0203 is: wink 10 times continuously –intermission –wink 2 times continuously –intermission - wink 10 times continuously –intermission –wink 3 times continuously.

2.3.3, DIAGNOSIS METER CONNECTION This system adopts “K” cable communication protocol and use ISO 9141-2 standard

diagnosis joint, please see chart 2.5. This standard diagnosis joint is connected to engine harness fixed. The pins of No.4, 7 and 16 on the standard diagnosis joint are used for EMS. The pin of No. 4 on standard diagnosis joint is ground wire; Pin of No.7 is connecting to No.71 pin of ECU, which is engine data “K”cable; No.16 pin is connecting to accumulator anode.

Chart 2.5 ISO9141-2 Standard Diagnosis Joint

2.3.4, READ MALFUNCTION INFORMATION BY WINK CODE

Switch on ignition switch and use engine data K cable(that is standard diagnosis joint 7#)to ground(use one lead connect pin of diagnosis joint 4# and pin of 7#) more than 2.5 seconds, if there are malfunction code in ECU malfunction memorizer, the malfunction light wink code of engine now is P-CODE value. Such as: P0203 winking type is: wink 10 times continuously – intermission – wink 2 times continuously – intermission - wink 10 times continuously –intermission –wink 3 times continuously.

3. WORKING PRINCIPLEAND CHARACTER OFEFI SYSTEM ELEMENT

3.1 ELECTRONIC CONTROL UNIT - ECU

1)Exterior drawing

2)Purpose: ECU accepts and deals with engine status signals inputted from sensors and

drives the actuators to work. Making engine working as the established program, insure power good, fuel consuming effectively and low emission.

3)Mounting position: Passenger compartment

4)Functions

 Multipoint injection in order  Control ignition

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

 Idle speed control  Knock control  Provide sensor power: 5V/100mA  Closed loop control  Control carbon canister solenoid valve  Air conditioner switch  engine malfunction indicator  Fuel fix quantity modification  Engine speed signal output(TN signal)  Input of speed signal  Malfunction self diagnosis  Accept engine loading signal etc.

5)Definition of pin Pin point Pin Connection point

1 Oxygen sensor heating 42 Air intake temperature 2 Ignition coil 2 43 3 Ignition 44 Non persistent power 4 Oxygen sensor heating 45 Non persistent power 5 Ignition coil 1 46 Canister valve

6 Injection nozzle 4(cylinder No. 2) 47

Injection nozzle 3(cylinder

7 Injection nozzle 2(cylinder No.3) 48 8 Engine speed 49

9 Coolant temperature 50 Fan control 1 10 Fuel consuming 51 electronically 2 11 Trouble light 52

No.4)

12 Persistent power 53 electronically 1 13 Ignition coil 54

Electronic throttle valve

14 Main relay 55 Downstream oxygen sensor 15 Engine speed sensor A 56

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

16 Accelerator position sensor 57 17 Sensor 1 58 Brake switch 18 Upstream oxygen sensor 59 Speed signal 19 Knock sensor A 60 Medium switch 20 Knock sensor B 61 Power 1 21 Brake light 62 CAN communication 22 63 Non persistent power 23 Accelerating sensor 64 24 65 25 66 26 67

Electronic throttle valve Electronic throttle valve Electronic throttle valve Electronic throttle valve

27 Injection nozzle 1(cylinder No.1) 68 Cooling fan 28 69 Air conditioner relay 29 70 Fuel pump relay 30 71 Diagnosis K cable 31 EOBD inspection light 72 32 5V power supply 2 73 Anti theft device 33 5V power supply 1 74 Clutch switch 34 Engine speed sensor B 75 Air conditioner switch 35 Sensor 3 76 Power steering switch 36 Sensor 2 77 Headlamp switch 37 Air flow sensor 78 Sensor 38 Electronic throttle valve control 79 Phase sensor 39 Engine coolant temperature sensor 80 Power 2 40 Accelerator position sensor 81 CAN communication 41 Air conditioner pressure

6)Normal working voltage: 9--16V

Normal working temperature: -40--70★

7)Malfunction phenomena and diagnosis method

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

 Malfunction phenomena: idle speed not stable, accelerating not good, can not start, idle

speed is too high, exhaust gas exceed standard, difficult to start, air conditioner failure, injector control failure, engine dies out etc..

 Reasons for general malfunction: 1, ECU component was burnt down caused by

overloading of the exterior connected electrical device; 2, circuit board was rust and erode caused by water in ECU.

 Service notice: 1, do not disassemble ECU at random during the service; 2, disassemble

accumulator 5 minutes prior to disassemble ECU; 3, keep the disassembled ECU carefully; 4, prohibit to connect any circuit to ECU connecting line.

 Simple measurement method:

1、(connect ECU joint)Read engine malfunction record by K line.

2、(disassemble ECU joint)Check the connecting line of ECU, and pay more attention to

check the power supply and ground line of ECU;

3、Check the working conditions of exterior sensor and its output signal and its circuit;

4、Check actuator and its circuit;

5、At last change ECU and have a test.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

3.2 COOLANT TEMPERATURE SENSOR

1)exterior drawing and pin

This sensor has two exchangeable pins.

2)Purpose: The sensor provide the coolant temperature signal to ECU for ignition timing and modifying fuel injection of starting, idle speed and normal working.

3)Installation position

Coolant temperature sensor was installed on the water outlet of cylinder block and the copper heat conducted socket was inserted into water. There are thread on the socket, and screw in coolant temperature sensor onto the threaded hole on cylinder block by the hexagon head of the socket. The maximum moment is 20Nm.

Chart 3-2 Outlook drawing of the

coolant temperature sensor

4)Working principle

This sensor is a thermistor of negative temperature coefficient (NTC), and its value will decrease with the coolant temperature increasing but the changes are not linearity. There are several different resistance values at different temperature:

T(★) Resistance value(kΩ)

-10 8.62----10.28 20 2.37----2.63 80 0.299----0.345

5)Normal working temperature: -30----130 ★ Normal working voltage: 5V DC

6)Malfunction phenomenon and diagnosis method

Coolant Temperature Sensor

Chart 3-3 Circuit diagram of coolant

temperature sensor

 Malfunction phenomenon: Difficult to

start.

 Reasons of malfunction: man made  Simple measurement method:

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

(Disassemble the joint)leave the digital multimeter at ohm shift and contact the No.1 and No. 2 pin of the sensor by its two meter pens. When it is 20★Rated the resistance is

2.5kΩ±5%. The other temperature can get

reference from above chart.

3.3 KNOCK SENSOR

1)Exterior drawing and pin

This sensor has three pins; No.1 and No.2 pin connect with ECU, and No. 3 pin connects with shield.

2)Purpose: This sensor provides engine

knock information to ECU, and carries out knock control.

3)Installation position

There is a hole in the middle of knock sensor, and the sensor is assembled on the block between No.2 and No.3 cylinder head. For the aluminum alloy block, using long bolt with 30mm long; for the casting iron, using 25mm long bolt. And the moment is 20±5Nm.

4)Working principle

Knock sensor is a kind of vibrating acceleration sensor and is assembled on cylinder block. The sense organ of the sensor is a piezoelectric element. The vibration of cylinder block is transferred to piezoelectric crystal by mass block inside of sensor. The piezoelectricity crystalloid gets pressure from mass block vibration, producing voltage on two polar and transferring vibration signals to voltage signal and output it. Because the frequency of knock vibration signal is much higher than the normal engine vibration signal, the ECU can separate the signal into knock signal and non knock signal.

Chart 3-4 Exterior drawing of knock

sensor

Knock sensor

Chart 3-5 circuit diagram of knock

sensor

5)Normal working temperature: -40--130★

6)Malfunction phenomenon and diagnosis method

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

sensor

 Malfunction phenomenon: badness

accelerating.

 Normal malfunction reason: all kinds of

liquid such as oil, coolant, braking liquid and water contact with sensor for a long time and erode the sensor.

 Simple measuring method: (disassemble the

joint) put digital multimeter at ohm shift, and contact the No.1, No. 2 and No.3 pin with its two meter pens. The resistance

value should be more than 1MΩ at normal

conditions. Leave the digital multimeter at millivolt shift, and tap around the sensor using little hammer, there should be voltage signal output.

3.4 OXYGEN SENSOR

1)Exterior drawing and pin

There are 4 pins on this oxygen sensor No. 1 connect to heating power anode (white) No. 2 connects to heating power cathode (white) No. 3 connects to signal cathode (gray) No. 4 connects to signal anode (black)

2)Installation position: Assemble it on the top of exhaust pipe.

3)Purpose: The oxygen sensor checks the

oxygen percent in exhaust gases and transfer the signal to ECU, and ECU will control the fuel closed loop according to this information. This will make engine working at its optimum conditions. And transfer and purify CO, HC, NOxcompound in 3-way catalytic converter of the tail gas maximally.

Chart 3-6 Exterior drawing of oxygen

sensor

Main relay

4)Working principle

Sensing element of oxygen sensor is a kind of ceramic tube with holes, and outside of tube walls are surrounded by engine exhaust gas and inside is air. Ceramic sensor element is a kind of solid state electrolyte with electrical heating

Oxygen sensor

Chart 3-7 circuit diagram of oxygen

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

tube inside. The working of oxygen sensor is carried out by transferring the concentration difference of the oxygen ion outside of ceramic tube to voltage (100mv— 900mv)signal and output.

5)Working voltage:12— 14V

6)Malfunction and diagnosis method

 Malfunction: badness idle speed, badness

acceleration, badness tail gas, over fuel consume etc.

 Reason: 1, moisture entering inside of

sensor, and when the temperature is changed pin is broken; 2, sensor poisoning( Pb,S,Br,Si)

 Notice: it is forbidden to use cleaning liquid,

oiliness liquid or volatility solid during service.

 Measuring method: a) disassemble joint,

put digital multimeter to ohm shift, connect meter pen to No.1(white) and No.2(white) pins of the sensor. Normally the resistance value is 1~6Ω. b) Connect the joint and keep it at idle speed status. When the oxygen sensor reaches to its working temperature 350★, keep digital multimeter to DC volt shift and connect meter pen to No.3 (gray) and No.4 (black) pins of sensor. Now the voltage should be fluctuate between 0.1- 0.9V quickly (the data also can be gotten from data flow inspected by diagnosis meter).

3.5 SPEED SENSOR (CRANKCASE POSITIONING SENSOR)

1)Exterior drawing and pin

No.1pin connects to shield No.2 and No.3 pin provide signal to ECU.

2)Installation position: on the flywheel plane at rear of engine.

Chart 3-8 Exterior Drawing Of Speed

Sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Service notice:

 For the inductive engine speed sensor, it is

permitted to take out from its pack before it is assembled to the auto or testing device right away.

 Inductive engine speed sensor is assembled

by press in method but not hammer tapping.

 Tightening torque is 8.2Nm. Gas clearance

between inductive engine speed sensor and pulse disc is 0.8 - 1.2mm.

3)Purpose: Speed sensor provides engine speed,

crankshaft angle and top dead center signal to ECU. That will control engine ignition and injection timing.

4)Working principle: The inductive engine

speed sensor work together with pulse disc, it is used in ignition system without distributor providing engine speed and crank shaft top dead center information. Speed sensor is made up of a permanent magnet and coil outside of magnet. Pulse disc is a tooth disc with 60 teeth originally but there are two teeth opening. Pulse disc is assembled on crank shaft and rotate with crankshaft. When the tip of the tooth passed the end of inductive engine speed sensor, the magnet pulse disc incises the magnetic line of force, generating rotating speed signal and output.

Speed sensor

5)Working temperature:-40--120★ Resistance of coil in room T:731--989Ω

6)Malfunction and diagnosis method:

 Malfunction: can not start etc.  Reason: man failure  Service notice: use pressing method but not

a hammer to install it.

 Simple measure method: disconnect the

joint, put digital multimeter to ohm shift, connecting two meter pen to No. 2 and No.

Chart 3-9 Circuit diagram of speed

sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Phase sensor

3 sensor connectors. The rated resistance is

860Ω±10% When it is 20★

3.6 PHASE SENSOR (CAM SHAFT POSITIONING SENSOR)

1)Exterior drawing and pin

This sensor has three pins: No. 1 grounding, No. 2 for signal output and No. 3 connecting to power anode.

2)Installation position: on the valve cover.

There is only one hole on this sensor casing for tightening M6, and the torque is: 8±0.5Nm.

3)Purpose: This sensor provides crankshaft

phase information to ECU, that is to say, to separate crankshaft compression top dead center and exhaust top dead center.

4)Working principle

Chart 3-10 Exterior drawing of phase

sensor

It is a Hall sensor.

5)Working temperature: -30--130★ Working voltage: 4.5— 16V Trigger gap: 0.1— 1.8mm

6)Malfunction and diagnosis method

 Malfunction: can not start, emission exceed

standard, fuel consume increased.

 Reason: Man made.  Simple measuring method: (connect the

joint) switch on ignition switch but do not start the engine; put digital multimeter on DC volt, connect two meter pen to No. 3 and No. 1 sensor connectors and make sure there is 12V reference voltage. Start the engine, checking if it is in good conditions of No. 2 pin by oscillograph on vehicle.

Grounding point

Connect to main relay

Chart 3-10 Exterior drawing of phase

sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Drawing of Electric

To Main

3.7 ELECTRIC FUEL PUMP

1)Exterior drawing and pin

The electric fuel pump has two pins connecting to pump relay. There are “+”and “-”showing anode and cathode on the pump housing near to pins.

2)Installation position: inside fuel tank

3)Purpose: Deliver the fuel to engine fuel

supplying pipe at certain flow and fuel pressure and keep the stable fuel pressure (realized by fuel pressure regulator)

4)Working principle

The electric fuel pump is made up of DC electromotor, vane pump and end cover (it’s an integration of check valve, relief valve and an anti electromagnetic interference element). Pump and electromotor are coaxial assembly and within the same casing. The pump and electromotor are full of gasoline for coolant and greasing inside of the casing. The accumulator provide power to electric fuel pump via fuel pump relay, and the relay switches on electric fuel pump only when engine starting and running. When the engine stops for some reason, the pump will stop to run by itself.

Chart 3-12 Exterior

Fuel Pump

5)Working voltage:8— 14V

6)Malfunction and diagnosis method

 Malfunction: big running noise, badness

 Reason: use of low quality fuel and cause 1,

 Service notice: 1, the electric fuel pump can

Working temperature:-30--70★ System pressure: 300KPa

acceleration, can not start (difficult to start) etc..

colloid became insulation layer; 2, fuel pump bushing and armature come to together; 3, components of fuel level sensor eroded.

Fuel Pump Relay

Electric Fuel Pump

Connect

Relay

Chart 3-10 Exterior Drawing Of Phase

Power Supply

Sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

has different flow according to the requirement of engine, but with the same exterior looking.

The pump which can be assembled to perhaps is not the fittest. For service the replaced electric fuel pump must has the same part number as the original pump; 2, do not change the pump at dry status to prevent the pump from accident; 3, when it needs changing fuel pump, please clean fuel tank and fuel filter.

 Simple measuring method: (disconnect joint)

leave digital multimeter at ohm shift, connect two meter pen to two pins of pump, measure the resistance, it is not zero or infinite(that is non short circuit, open circuit).(connect the joint)connect the fuel pressure meter to fuel intake pipe and start the engine, observing if the fuel pump works; If it is not running, check if there is power or not on the pin of”+”; if it is running, at the condition of idle speed, check the fuel pressure if it is around 260kPa; plug off the fuel pressure regulator vacuum pipe if it is around 300kPa.

Chart 3-14 Exterior Drawing of Injector

3.8 ELECTROMAGNETIC INJECTOR

1)Exterior drawing and pin

There are two pins on each injector. One of them is No. 87 pin aside of casing marked with plus and connected to main relay output; and another one connect with ECU No. 27,6,7,47 pins.

2)Installation position: On the air intake manifold

near the end of air intake port. When you .disassemble and reassemble the fuel injector the O ring must be changed. And pay attention not to damage the sealing surface of the injector.

3)Purpose: Inject some fuel to its correspondent

cylinder at proper time to meet the engine requirement of different power and different torque.

4)Working principle: ECU sends electrical

impulse to injector coil and form magnetic field force. When magnetic field force increase to

1, O Ring 2, Screen 3, Injector with Elec. Plug 4, Coil 5, Spring 6, Valve Pin with Coil Armature 7, Valve Seat with Injection Hole

Chart 3-15 Cutaway View Of Injector

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

To Main

Drawing of Airflow

conquer Return spring pressure, needle valve gravity and friction force, the needle valve begin to rise up and start the injection process. The pressure of return spring makes needle valve close again when the injection impulse is stopped.

5)Working voltage:6— 16V

Working injection pressure: 350KPa

6)Malfunction and diagnosis method

 Malfunction: badness idle speed, badness

acceleration, can not start (difficult to start) etc..

 Reason: lack of maintenance causes invalid by

the colloid inside of injector became insulation layer.

 Simple measure method: (disconnect the joint)

leave digital multimeter at ohm shift, connect the meter pen to the two pins of injector. The rated resistance should be 11 - 13Ωwhen it is 20★.

3.9AIR FLOW SENSOR

1)Exterior drawing and pin definition

This sensor is 5 pins: No. 1 is intake temperature pressure signal; No. 2 is accumulator pressure; No. 3 is grounding; No. 4 is reference voltage 5V; No. 5 is intake airflow signal output.

Connect Relay Pin No. 87

Cylinder No.1, No.2, No.3, No.4

Chart 3-16 Circuit Diagram of Injector

2)Installation position

It is behind the air cleaner of the air intake tube.

3)Purpose:

This sensor is hot cable airflow sensor, which check the temperature and air intake flow entering to cylinder and provide evidence to ECU to calculate fuel injection quantity.

4)Working principle

If there are no airflow passing when the air quality and flow meter works, temperature grads of both sides of the heating area spread symmetry, and temperature of these two points are same. When the air passes here just one way, the air will be heated when it passes the central heating area and this will

Chart 3-17 Exterior

Sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

make the heat exchange different of the heat diaphragm of both sides.

This will make the temperature of two sensing element measuring point inside of the flowmeter Changes differently and appears difference in temperature. And the difference of the temperature will increase with the increase of the airflow. Big/small and positive/negative of the temperature difference improved the quality and direction of the airflow. And the inside evaluate circuit will transfer the temperature difference to voltage signal and output.

5)Working temperature:-40--125★

6)Malfunction and diagnosis method

 Reason: sensing element is polluted by the dust

particle, oil and water and causes the part invalid.

 Service notice: 1, it is prohibited to use erosion

liquid to clean sensing element during service; 2, not to use high pressure air to impact sensing element; 3, make sure there are no dust into air pipe when you change air cleaner and no unqualified air into air cleaner.

 Simple measuring method: static measurement:

(zero flow measurement) No. 3 grounding; No. 4 input 5V reference voltage; No.2 input 14V rated voltage; check No. 5 output voltage, if the output is bigger than 1.025V, we can confirm the function of this sensor is not qualified. Dynamic measurement: if it is confirmed the sensor is broken, connect a tail gas analysis meter to exhaust pipe and check it by using “two working conditions method”: 1, idle speed working conditions; 2, 2000rpm stable working conditions.

Check the reading of HC 、CO、CO2, normally HC<100ppm CO<0.5%,CO2>13.5%

3.10 DOUBLE SPARK IGNITION COIL

1)Exterior and pin definition

No. 1 coil primary winding connect with No.5 pin of ECU; No. 2 coil primary winding connect with No. 2

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

xterior Drawing of Ignition

pin of ECU; No. 3 and No.4 pins connect with power anode.

2)Installation position: on the engine

3)Purpose: Ignition coil transfers the low voltage of

primary winding to high voltage of secondary winding, and produce spark by spark plug discharging then burning the combustible gas inside of the cylinder.

4)Working principle

Ignition coil ZS - K22 is made up of two primary windings, two secondary windings, mandrel, and casing. When one of the primary windings grounding chunnel is connected, the primary winding is in charging. Once the circuit is cut off by ECU, the charging is stopped. At the same time the high voltage is sensed in the secondary winding and making the spark plug discharging. There is a different with the distributor ignition coil: for the ignition coil ZS - K22, there is one spark plug on both side of the secondary winding, and the both spark plugs can ignite at the same time. These two primaries connect and disconnect to power alternatively. And correspondently these two secondary windings discharge alternatively.

Chart 3-18 E

Coil

5)Working voltage:14V

Working temperature:-40— 120★

6)Malfunction and diagnosis method

 Malfunction: can not start.  Reason: current is too big and got burnt, damaged

by outside force etc..

 Service notice: forbid to use "short circuit test

igniting method” to test ignition function, prevents the electronic controller from damaging.

 Simple measuring method: (disassemble the joint)

leave digital multimeter at ohm shift, connect two meter pen to two pins of primary winding, the resistance value is 0.42- 0.58Ωwhen it is 20★; secondary winding resistance value is 11.2-

14.8kΩ.

Connect To Main Relay Pin No.87

Chart 3-19 circuit Diagram of Ignition

Coil

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Exterior Drawing of Canister

Soleno

3.11 CARBON CANISTER SOLENOID VALVE

1)Exterior drawing and pin definition

Canister control valve only has two pins; one is connect to No.87 pin of main relay output end; and another pin connected to No. 5 pin of ECU.

2)Installation position: Canister vacuum pipe of intake manifold

3)Purpose: Control the quantity of the cleaning flow from canister to air intake chief pipe. The absorption of the canister is limited so if the gasoline vapor adhesive to canister can not be consumed the gasoline vapor will volatility to outside and pollute the air.

4)Working principle

Chart 3-20

Canister is made up of electromagnetic coil, armature and valve etc.. There is strainer on the intake. The flow quantity passes canister valve is correlate not only to electrical impulse duty ratio of canister control valve output by ECU, but also to the pressure difference between canister valve intake and outlet. When there is no electronic impulse, the canister control valve will shut down.

5)Working voltage:9— 16V

Working temperature:-30--120★

6)Malfunction and diagnosis method

 Malfunction: Function invalidation.  Reason: some particle coming to inside of valve

causes erosion or poor sealing.

 Service notice: 1, let the airflow direction be

accord with the regulation; 2, when there are black particle inside of valve and causes the control valve invalidation, the valve need to be changed, please check the canister working conditions; 3, avoid the water, fuel and other liquid into valve during the service; 4, hang the valve on the tube to avoid the transferring of solid sound.

Connect To Main Relay

Canister Solenoid Valve

Chart 3-21 Circuit Diagram of Canister

Solenoid

 Simple measurement method: (disassemble the

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

joint) leave digital multimeter to ohm shift, two meter pen connect to the pins of canister valve, it is 26±4 Ω when it is 20★.

3.12 FUEL PRESSURE REGULATOR

1)Exterior drawing

2)Installation position: Fuel bracket assembly

3)Purpose: Adjust the pressure inside of fuel pipe,

keep the System pressure around 350Kpa.

4)Working principle: See chart 3- 23, one piece of flexible film made up of rubber and fiber separate the fuel pressure regulator into two compartments. The upper compartment communicates to the air, and there is spring inside. The lower compartment is full of fuel entering from the fuel intake under the fuel pressure regulator. The lower part of the film gets the pressure from fuel and the upper part gets the pressure from air and spring. The film can distort and drive valve seat making the valve open and close, but the distortion is smaller the acting force of the spring may be seemed as not changed. So the opening and closing of the valve is decided by the pressure difference of the fuel pressure from lower compartment and the air pressure from the upper compartment. If the valve is closed at first, then the fuel pressure increased causing the pressure difference between upper and lower compartments increased. At last the film was raised up by the fuel pressure and valve is opened. The fuel return to fuel tank from oil return port of pressure regulator, the fuel pressure decreased until the valve is closed. If the engine changes its working conditions now, the pressure difference of fuel system and the air pressure is about the same.

Chart 3-22 Fuel Pressure Regulator

5)Malfunction and diagnosis method

 Malfunction: fuel pressure is too high or too low,

difficult to start.

 Reason: long time using without maintenance

causing: 1, strainer jammed; 2, particle causes big leaking; 3, man made mechanical damages.

 Service notice: 1, prohibit to use high pressure air

blowing film element; 2, Forbid using strong

Chart 3-23cutaway View of Fuel

Pressure Regulator

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

causticity liquid to wash it; 3, avoid it from distorting by outside force.

Simple measurement method: connect fuel pressure gauge at fuel intake pipe, start the engine and make the engine running at idle speed; check the fuel pressure around 350kPa or not; step on the gas until the engine speed to 2500rpm,and observe if the fuel pressure at around 350kPa.

3.13 ELECTRONIC THROTTLE VALVE AND

ACCELERATOR

1)Exterior drawing and pin

 Accelerator pin definition

Pin No.1 and No.2 is the anode of the 5V reference voltage

Pin No.3 and No.5 is the cathode of 5V reference voltage

Pin No. 4 and No. 6 is output voltage signal

Accelerator Pedal

Electronic Throttle Valve

 Electronic throttle valve pin definition

Pin No. 1 is motor anode. Pin No. 2 is potentiometer anode. Pin No. 3 is potentiometer cathode. Pin No. 4 is motor cathode. Pin No. 5 is signal output 1.

Pin No. 5 is signal output 2.

2)Installation position: Electronic throttle valve: front end of intake manifold; accelerator: driver cockpit.

3)Working principle: The engine on time torque requirement was transferred from accelerator to ECU, and ECU sends impulse electronic signal to electronic throttle valve according to torque requirement information; the motor is running and drive throttle valve to its opening required degrees; this throttle valve can stay at one fixed position or change to another position upon required to meet the

Chart 3-24 Electronic Throttle Valve

and Accelerator

Chart 3-25 Circuit Diagram of

Accelerator

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

requirement of the engine working conditions according to the impulse signal frequency and width of impulse.

3.14 FAN CONTROL

ECU control the fan according to water temperature of the engine and the requirement signal and control the fan system delay at the fit conditions.

1) Conditions for fan running at low speed: a) Engine coolant temperature between 96★ to

102★.

b) There is air conditioner requirement and the

air conditioning compressor begins to work.

2) Conditions for fan running at high speed: a) Engine coolant temperature sensor broken b) Engine coolant temperature higher than

102★.

3) Conditions of fan continue to work after the

engine stops working

A) Engine air intake temperature sensor is

broken and delay 60 seconds.

B) Engine coolant temperature sensor is broken

and delay 60 seconds.

C) Engine coolant temperature higher than

100.5★, high speed delay 60 seconds.

D) Temperature of intake air more than 70.5★,

delay 60 seconds.

4) Malfunction diagnose Short circuits from high relay line to power

supply

High-Speed Relay Of Fan

Low-Speed Relay Of Fan

Power Supply

Double-Speed Fan

Short circuits from high-speed relay line to

ground Open circuits of high-speed relay line Short circuits from low-speed relay to power

supply

Chart 3-26 Fan control schematic

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Signal

Form Air

Short circuits from low-speed relay line to

ground Open circuits of low-speed relay line Engine coolant temperature sensor failure Engine intake air temperature sensor failure

3.15AIR CONDITIONER CONTROL

1)Working principle Switch on the air conditioner and blower; air

conditioner pressure is regular; evaporator temperature sensor inspect the right data; requirement signal of air conditioner is sending by these switches to ECU, and ECU controls air conditioning relay attracting and provide rotating speed signal to step motor and open the electronic fan and air conditioning chart to work.

2)Air conditioner control strategy a) The air condition can be switched on after 5

seconds of the engine starts. b) Cut off the air conditioner when temperature of

intake air higher than 140.3★. c) Cut off air conditioner when the coolant

temperature higher than 114.8★; resume the air

conditioning control after its lower than 11.8★. d) Cut off air conditioner when the engine speed is

higher than 6520rpm or lower than 520rpm. e) Cut off air conditioner when the pressure inside

of air conditioner high pressure pipe is higher

than 20bar and resume the control when the

pressure is lower than 9.5bar. f) Cut off air conditioner when the evaporator

temperature is lower than 1.5★; and resume the

control when it is higher than 4.5★. g) Cut off air conditioner when the system pressure

is lower than 8.04V; consume the control when

it is higher than 10.01V.

Power Supply

Request

Conditioner

Air Conditioner Compressor Clutch

Chart 3-27 Air conditioner control

schematic

3) Malfunction diagnosis

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Blower circuit malfunction (fuse is burnt, relay circuit is open circuit or short circuit)

Irregular pressure of air conditioner (much higher of the high voltage or the much lower of the low voltage)

Malfunction of evaporator temperature sensor Air conditioner relay circuit is failure (short circuit

to ground, short circuit to power supply, open circuit).

4 ME7 SYSTEM TEST AND REPAIRACCORDING TO TDC

Explanation:

1. When it is confirmed that malfunction is steady we can carry out the test and repair as

below, otherwise this will cause wrong diagnosis.

2. There is multimeter mentioned below, it is referred to digital multimeter; prohibit to use

finger multimeter check the EFI system.

3. Check and repair the vehicle with anti theft system please re-program the replaced ECU

when there is the occasion of changing the ECU at “flow up steps”.

4. In this items when the TDC of P0171、P0172、P0335、P0336、P1651 existing, the engine

trouble light will not light on.

5. If it shows much lower of the voltage in some circuit in DTC explanation, it refers to

perhaps there is ground short circuit inside of this circuit; If it shows much higher of the

voltage in some circuit in DTC explanation, it refers to perhaps there is power supply

short circuit inside of this circuit; If it shows circuit failure in DTC explanation, it refers

to perhaps there is open circuit or multi circuit malfunction inside of this circuit.

Diagnosis help: 1. DTC can not be deleted; it is steady failure; if it is occasional failure,

check if it is because of the loosening of cable joint.

2. Check according to the above steps and find noting wrong;

3. During check and repair pay attention that the influence of vehicle maintenance, cylinder pressure and mechanical ignition timing to the system;

4. Change ECU and test it. If the DTC can be deleted, the malfunction is inside of ECU; if the DTC can not be deleted, change back to the original ECU and check it again according to above items.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

erature is much higher indicated by

Temperature is much higher indicated by

Rotating speed of idle speed is lower

Much higher voltage of upstream oxygen

conditioner compressor relay control

4.1 ENGINE DTC (DIAGNOSTIC TROUBLE CODE) LIST DTC Definition DTC Definition

P0107

P0108

P0112

P0113

P0117

Much lower voltage of the air intake

pressure sensor

Much higher voltage of the air intake

pressure sensor

Indicated temperature is much lower of

the air intake temperature sensor

Temp

the air intake temperature sensor

Temperature is much lower indicated by

engine coolant temperature sensor

P0340 Phase sensor signal failure

P0342

P0343

P0443

Much lower voltage of the phase

sensor

Much higher voltage of the phase

sensor

Canister control valve drive grade

control circuit failure

Much lower voltage of canister

P0444

control valve drive grade control

circuit

Much higher voltage of canister

P0118

P0122

P0123

P0130

P0132

engine coolant temperature sensor

The circuit voltage of throttle position

sensor is much lower

The circuit voltage of throttle position

sensor is much higher

Unreasonable failure of the upstream

oxygen sensor signal

sensor

P0134 Signal failure of upstream oxygen sensor P0508

P0135

P0171

P0172

Heating circuit failure of upstream

oxygen sensor

Closed loop air fuel ratio control self

adapting exceeds it maximum limit

Closed loop air fuel ratio control self

adapting exceeds it minimum limit

P0445

control valve drive grade control

circuit

P0480

Air conditioner condenser cooling

fan relay control circuit failure

P0500 Unreasonable failure of speed signal

P0506

P0507

than target idle speed

Rotating speed of idle speed is

higher than target idle speed

Idle speed regulator control circuit

voltage is too low

P0509

P0511

Idle speed regulator control circuit

voltage is too high

Idle speed regulator control circuit

failure

P0560 System voltage signal unreasonable

P0201 The 1st cylinder injector circuit failure P0562 System voltage is too low P0202 The 2nd cylinder injector circuit failure P0563 System voltage is too high P0203 The 3rd cylinder injector circuit failure P0601 ECU testing code failure P0204 The 4th cylinder injector circuit failure P0602 ECU diagnosis data ID code failure

P0230 Fuel pump control circuit failure P0645

Air conditioner compressor relay

control circuit failure

Much lower voltage of air

P0325 Knock sensor circuit failure P0646

circuit

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

conditioner compressor relay control

put the

if it is

check the voltage between pin No. 3 and pin No. 1 by

Check if it is short circuit to ground between ECU pin

Check if it is open circuit or short circuit to power supply

Much higher voltage of air

P0335 Crank shaft position sensor signal failure P0647

circuit

P0336

Crank shaft position sensor signal

unreasonable failure

P1651 Trouble light control circuit failure

4.2 DIAGNOSIS FLOW WHEN THERE IS DIFFERENT DTC

P0107 Much lower voltage of the air intake pressure sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator,

ignition switch to “ON”

Observe “air intake pressure”item in data flow,

about 101kpa (specific data is correlated to that time

air pressure).

Take off the joint of cable air intake pressure sensor,

Yes To step No. 5

No Next steps

Yes To step No. 5

Next step

multimeter and look if it is around 5V.

No. 17, No. 33, No. 37 and sensor connector No.1,

No.3 and No. 4.

No Next step

Yes

Repair or replace

cable4

No Next step

Start the engine at idle speed. Step on the accelerator

slowly approach to open completely and observe the

value changes of diagnostic tester “air intake

pressure”, the changes should be not big; step on the

accelerator quickly to complete open, the displayed

Yes Diagnosis help

No Replace the sensor

value should be reach up to 90kpa instantaneous.

DTC: P0108 Much higher voltage of the air intake pressure sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Observe “air intake pressure”item in data flow, if it is

about 101kpa(specific data is correlated to that time air

pressure)

Take off the joint of cable air intake pressure sensor,

check the voltage between pin No. 3 and pin No. 1 by

multimeter and look if it is around 5V.

between ECU pin No. 17, No. 33, No. 37 and sensor

connector No.1, No.3 and No. 4.

Next step

Yes To step No. 5

No Next steps

Yes To step No. 5

No Next step

Yes

Repair or replace

cable4

No Next step

Yes Diagnosis help5 Start the engine at idle speed. Step on the accelerator

slowly approach to open completely and observe the

No Replace the

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

value changes of diagnostic tester “air intake pressure”,

the changes should be not big; step on the accelerator

quickly to complete open, the displayed value should be

reach up to 90kpa instantaneous.

sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

if it is

Check if it is open circuit or short circuit to power supply

if it is

★ there is perhaps open

DTC P0112 Circuit voltage is much lower of the throttle position sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Observe “air intake temperature”item in data flow,

same temperature with air intake pipe(specific data is

correlated to the engine temperature at that time)

Notice: if the value is - 40★ there is perhaps open circuit

failure in the circuit.

Take off the joint of cable air intake temperature sensor,

check the resistance values using multimeter between

sensor connector No. 1 and No. 2 and check if it is

corresponding to its temperature (please reference the

related section of this service manual)

Take off the joint of cable air intake temperature sensor,

check the voltage between pin No.1 and pin No.2 by

multimeter and look if it is around 5V.

between ECU pin No. 17, No. 40 and sensor connector

No.1, No.2

Next step

Yes To step No. 5

No Next step

Yes Next step

No Replace sensor

Yes To step 5

No Next step

Repair or

Yes

replace

cable

No Next step

Start the engine at idle speed. Observe the value changes

of diagnostic tester “air intake temperature”, the value

should increase with the increase of the engine intake air.

Yes Diagnosis help

Replace the

sensor

DTC: P0113 Temperature is much higher indicated by the air intake temperature sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Observe “air intake temperature”item in data flow,

Next step

Yes To step No. 5

same temperature with air intake pipe(specific data is

correlated to the engine temperature at that time)

Notice: if the value always is - 40

No Next step

circuit failure in the circuit.

Take off the joint of cable air intake temperature sensor,

Yes Next step

check the resistance values using multimeter between

sensor connector No. 1 and No. 2 and check if it is

corresponding to its temperature (please reference the

No Replace sensor

related section of this service manual).

Take off the joint of cable air intake temperature sensor,

check the voltage between pin No.1 and pin No.2 by

multimeter and look if it is around 5V.

Yes To step 5

No Next step

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Repair or

Check if it is short circuit to ground between ECU pin

No. 17, No. 40 and sensor connector No.1, No.2

Yes

replace

cable

No Next step

Start the engine at idle speed. Observe the value changes

of diagnostic tester “air intake temperature”, the value

should increase with the increase of the engine intake air.

Yes Diagnosis help

Replace the

sensor

DTC: P0117 Temperature is much lower indicated by engine coolant temperature sensor.

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “ON”.

Observe “coolant temperature”item in data flow, if

Next step

Yes To step 6

it is same temperature with engine temperature

(specific data is correlated to the engine temperature

at that time).

No Next

Notice: if the value always is - 40★ there is perhaps

open circuit failure in the circuit.

Take off the joint of coolant temperature sensor on

Yes Next step

the cable, check the resistance values using

multimeter between sensor connector No. 1 and No.

2 and check if it is corresponding to its temperature

No Replace sensor

(please reference the related section of this service

manual).

Take off the joint of coolant temperature sensor on

the cable, check the voltage between pin No.1 and

pin No.2 by multimeter and observe if it is around

Yes To step 6

No Next step

5V.

Check if it is open circuit or short circuit to power

supply between ECU pin No.39, No. 35 and sensor

connector No.1, No.2.

Start the engine at idle speed. Observe the value

changes of diagnostic tester “coolant temperature”,

the value should increase with the increase of the

Yes

No Next step

Yes Diagnosis help

No Replace sensor

Repair or replace

cable5

engine coolant temperature.

DTC: P0118 Temperature is much higher indicated by engine coolant temperature sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “ON”.

Observe “coolant temperature”item in data flow, if

it is same temperature with engine temperature

(specific data is correlated to the engine temperature

Next step

Yes To step 6

No Next

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

at that time).

Notice: if the value always is - 40★ there is perhaps

open circuit failure in the circuit.

Take off the joint of coolant temperature sensor on

Yes Next step

the cable, check the resistance values using

multimeter between the sensor connector No. 1 and

the No. 2 and check if it is corresponding to its

No Replace sensor

temperature (please reference the related section of

this service manual).

Take off the joint of coolant temperature sensor on

the cable, check the voltage between pin No.1 and pin No.2 by multimeter and observe if it is around

Yes To step 6

No Next step

5V.

Check if it is short circuit to ground between ECU

pin No.39, No. 35 and sensor connector No.1, No.2.

Yes

Repair or replace

No Next step

cable

Start the engine at idle speed. Observe the value

changes of diagnostic tester “coolant temperature”,

the value should increase with the increase of the

Yes Diagnosis help

No Replace sensor

engine coolant temperature.

DTC: P0122 Indicated temperature is much lower of the air intake temperature sensor.

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “ON”. Observe “throttle valve absolute opening”item in data flow, check the value if it is between 4% and

10% (specific data is correlated to the vehicle type).

Step on the accelerator slowly to complete opening

Next step

Yes Next step

No To step No. 5

Yes Next step

and observe “throttle valve absolute opening”item

in data flow, check if the value is increased to around

85-90% with the opening of the throttle valve

No To step No. 5

(specific data is correlated to the vehicle type).

Repeat step 3 and observe “throttle valve absolute

opening”item in data flow, and check if there is

jump during the changes.

Take off the joint of throttle valve positioning sensor

on the cable, check if there is short circuit to ground

Yes Replace the sensor

No Next step

Yes

Repair or replace

cable

between pin No.17, No.32, No.16 of ECU and pin

No.1, No.2, No.3.

No Next step

Check the voltage between pin No.1 and pin No.2 by

multimeter and observe if it is around 5V.

Yes Replace sensor

No Diagnosis help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0123 Circuit voltage is much higher of the throttle position sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “ON” Observe “throttle valve absolute opening”item in data flow, check the value if it is between 4% and

10% (specific data is correlated to the vehicle type).

Step on the accelerator slowly to complete opening

Next step

Yes Next step

No To step No. 5

Yes Next step

and observe “throttle valve absolute opening”item

in data flow, check if the value is increased to around

85-90% with the opening of the throttle valve

No To step No. 5

(specific data is correlated to the vehicle type).

Repeat step 3 and observe “throttle valve absolute

opening”item in data flow, and check if there is

jump during the changes.

Take off the joint of throttle valve positioning sensor

on the cable, check if there is open circuit or short

Yes Replace the sensor

No Next step

Yes

Repair or replace

cable

circuit to power supply between pin No.17, No.32,

No.16 of ECU and pin No.1, No.2, No.3 of sensor

No Next step

Check the voltage between pin No.1 and pin No.2 by

multimeter and observe if it is around 5V.

Yes Replace sensor

No Diagnosis help

DTC: P0130 Unreasonable failure of the upstream oxygen sensor signal (Notice: below diagnosis process is fit for those without P0135 at the same time; if there is

P0135 failure, please deal with P0135 failure at first and then check as below.)

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “ON”

Start the engine and leave it at idle speed until its

Next step

Yes Diagnosis help

coolant reaches to the normal value. Observe the

value changes of “oxygen sensor voltage”item on

diagnostic meter, the displayed value should change

No Next step

rapidly from 100mV-900mV.

Check if there is short circuit to ground between pin

No.36, No.18, of ECU and pin A (opposite to oxygen

sensor gray connecting line), B (opposite to oxygen

sensor black connecting line).

Yes

No Next step

Repair or change

cable

DTC: P0132 Much higher voltage of upstream oxygen sensor (Notice: below diagnosis process is fit for those without P0135 at the same time; if there is

P0135 failure, please deal with P0135 failure at first and then check as below.)

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Start the engine and leave it at idle speed until its

ignition switch to “ON”.

Yes Diagnosis help

Next step

coolant reaches to the normal value. Observe the value

changes of “oxygen sensor voltage”item on diagnostic

meter, the displayed value should change rapidly from

No Next step

100mV-900mV.

Check if there is short circuit to power supply between

pin No.36, No.18, of ECU and pin A(opposite to

Yes

Repair or change

cable

oxygen sensor gray connecting line), B (opposite to

oxygen sensor black connecting line).

A, check if the exhaust system is jammed

B, check if the injector is leaking

C, check if the fuel pressure is over higher

D, check if the valve clearance is over smaller etc.

No Diagnosis help

Check and repair

Yes

according to

diagnosis

No Diagnosis help

DTC: P0134 Signal failure of upstream oxygen sensor (Notice: below diagnosis process is fit for those without P0135 at the same time; if there is

P0135 failure, please deal with P0135 failure at first and then check as below.)

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Start the engine and leave it at idle speed until its

ignition switch to “ON”.

Yes Diagnosis help

Next step

coolant temperature reaches to the normal value.

Observe the value changes of “oxygen sensor voltage”

item on diagnostic meter, the displayed value should

No Next step

change rapidly from 100mV-900mV.

Check if there is open circuit between pin No.36,

No.18, of ECU and pin A (opposite to oxygen sensor

Yes

Repair or change

cable

gray connecting line), B (opposite to oxygen sensor

black connecting line) of sensor joint.

No Diagnosis help

DTC: P0135 Heating circuit failure of upstream oxygen sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Take off the oxygen sensor joint on the cable and

ignition switch to “ON”.

Yes Next step

Next step

check the voltage between the pins of C (opposite to

oxygen sensor white connecting line) and D (opposite

to oxygen sensor white connecting line) by multimeter,

No To step No.4

and observe if it is about 12V.

3 Check the resistance value between oxygen sensor Yes Next step

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

connectors C (white) and D (white) using multimeter,

and observe if it is 2-5Ω when it is 20★.

Check the fuse inside of oxygen sensor heating circuit

and observe if it is blow.

Check if there is open circuit or short circuit to power

supply between ECU pin No.1, main relay sensor

No.87 and pin C (opposite to oxygen sensor white

connecting line), D (opposite to oxygen sensor white

No Change sensor

Yes Change fuse

Next step

Yes

Repair or change

cable

No Diagnosis help

connecting line) of sensor joint.

DTC: P0171 Closed loop air fuel ratio control self adapting exceeds it maximum limit (Notice: below diagnosis flow is fit for when air intake pressure sensor failure, canister

control valve failure and oxygen sensor failure are not appeared at the same time; if there are failures existing at the same time please deal with other failures at first and then do as below.)

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Start the engine and leave it at idle speed until its

Next step

Yes Next step

coolant temperature reaches to the normal value.

Observe the value changes of “oxygen sensor voltage”

item on diagnostic meter, and the displayed value keeps

No Diagnosis help

around the value of 100mV at some working conditions.

Connect the fuel pressure meter (connection position is

the front end of fuel distributing pipe assembly fuel

intake pipe); start the engine and check the fuel pressure

Yes

Repair or replace

the cable

at idle speed conditions if it is around 260kpa; take off

the vacuum pipe on fuel pressure regulator, check the

No Next step

pressure and observe if it is around 300kpa.

Check if there is short circuit to ground between ECU

pin No.36, No.18 and pin A(opposite to oxygen sensor

Yes

Repair or replace

cable

gray connecting line), pin B (opposite to oxygen sensor

black connecting line) of sensor joint.

A, check if there is a heavy leaking in air intake system

B, check if the injector is jammed

C, check if the clearance of spark plug is too big D, check if the sub live wire resistance is too big

No Next step

Yes

Repair according

to diagnosis data

No Diagnosis help

E, check if the valve clearance is too big etc.

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0172 Closed loop air fuel ratio control self adapting exceeds it minimum limit

(Notice: below diagnosis flow is fit for when air intake pressure sensor failure, canister control valve failure and oxygen sensor failure are not appeared at the same time; if there are failures existing at the same time please deal with other failures at first and then do as below.)

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Start the engine and leave it at idle speed until its

ignition switch to “ON”

Yes Next step

Next step

coolant temperature reaches to the normal value.

Observe the value changes of “oxygen sensor voltage”

item on diagnostic meter, and the displayed value

No Diagnosis help

keeps around the value of 900mV at some working

conditions.

Connect the fuel pressure meter (connection position is

the front end of fuel distributing pipe assembly fuel

intake pipe); start the engine and check the fuel

pressure at idle speed conditions if it is around 260kpa;

take off the vacuum pipe on fuel pressure regulator,

Yes

Repair or replace

the cable

Check and repair

fuel system

check the pressure and observe if it is around 300kpa.

Check if there is short circuit to power supply between

ECU pin No.36, No.18 and pin A (opposite to oxygen

Yes

Repair or replace

cable

sensor gray connecting line), pin B (opposite to

oxygen sensor black connecting line) of sensor joint.

A, check if the injector is leaking

B, check if the exhaust pipe is jammed

C, check if the valve clearance is too small etc.

No Next step

Yes

Repair according

to diagnosis data5

No Diagnosis help

DTC: P0201 The 1stcylinder injector circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the 1stcylinder injector joint from the cable,

check the voltage value between this joint pin No.1

and the power cathode by multimeter and observe if it

Yes To step No.4

No Next step

Next step

is 12V.

Check if there is open circuit or short circuit to ground

between the 1stinjector joint pin No.1 and main relay.

Yes

Repair or replace

the cable3

No Next step

Check the resistance value by multimeter between 1

cylinder injector pin No.1 and No.2, and observe if it

Yes Next step

No Change injector

is 11-13Ω when it is 20℃.

5 Check the voltage value by multimeter between 1

Yes Repair according to

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

diagnosis datacylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

Check if there is open circuit or short circuit to ground

between 1stcylinder injector joint pin No.2 and the

ECU pin No.27.

No Diagnosis help

Yes

Repair or replace

cable6

No Diagnosis help

DTC: P0202 The 2ndcylinder injector circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the 2ndcylinder injector joint from the cable,

check the voltage value between this joint pin No.1

and the power cathode by multimeter and observe if it

Yes To step No.4

No Next step

Next step

is 12V.

Check if there is open circuit or short circuit to ground between the 2ndinjector joint pin No.1 and main relay.

Yes

Repair or replace

the cable3

No Next step

Check the resistance value by multimeter between 2

cylinder injector pin No.1 and No.2, and observe if it

Yes Next

No Change injector

is 11-13Ω when it is 20℃.

Check the voltage value by multimeter between 2

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

Check if there is open circuit or short circuit to ground

between 2ndcylinder injector joint pin No.2 and the

ECU pin No.6.

Yes Diagnosis help

No Next step

Yes

Repair or replace

cable6

No Diagnosis help

DTC: P0203 The 3rdcylinder injector circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the 3rdcylinder injector joint from the cable,

check the voltage value between this joint pin No.1

and the power cathode by multimeter and observe if it

Yes To step No.4

No Next step

Next step

is 12V.

Check if there is open circuit or short circuit to ground

between the 3rdinjector joint pin No.1 and main relay.

Yes

Repair or replace

the cable3

No Next step

Check the resistance value by multimeter between 3

cylinder injector pin No.1 and No.2, and observe if it

Yes Next step

No Change injector

is 11-13Ω when it is 20℃.

5 Check the voltage value by multimeter between 3

Yes Diagnosis help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

Check if there is open circuit or short circuit to ground

between 3rdcylinder injector joint pin No.2 and the

ECU pin No.7.

No Next step

Yes

Repair or replace

cable6

No Diagnosis help

DTC: P0204 The 4thcylinder injector circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the 4thcylinder injector joint from the cable,

check the voltage value between this joint pin No.1

and the power cathode by multimeter and observe if it

Yes To step No.4

No Next step

Next step

is 12V.

Check if there is open circuit or short circuit to ground

between the 4thinjector joint pin No.1 and main relay.

Yes

Repair or replace

the cable3

No Next step

Check the resistance value by multimeter between 4

cylinder injector pin No.1 and No.2, and observe if it

Yes Next step

No Replace injector

is 11-13Ω when it is 20℃.

Check the voltage value by multimeter between 4

cylinder injector pin No.2 and power supply cathode,

and observe if it is around 3.7V.

Check if there is open circuit or short circuit to ground

between 4thcylinder injector joint pin No.2 and the

ECU pin No.47.

Yes Diagnosis help

No Next step

Yes

Repair or replace

cable6

No Diagnosis help

DTC: P0230 Fuel pump control circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Take off the fuel pump relay and put ignition switch to

Yes To step No.4

Next step

“ON”; check the voltage separately between fuel

pump relay power supply ends - that is relay pin No.

30 and No.86 and power supply cathode, and observe

No Next step

if it is around 12V.

Check if there is open circuit or short circuit to ground

of the relay power supply ends circuit.

Yes

Repair or replace

the cable3

No To step No.2 Check the voltage by multimeter between fuel pump relay control ends that is relay pin No. 85 and power

supply cathode and observe if it is around 3.7V.

5 Check if there is open circuit or short circuit to ground

Yes

No Next step

Yes Repair or replace

Replace fuel

pump relay4

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

cableor to power supply between relay control ends that is

relay pin No.85 and ECU pin No.69.

No Diagnosis help

DTC: P0325 Knock sensor circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Take off the knock sensor joint from the cable; check

the resistance value by multimeter between knock

sensor connector No.1and No.2 and observe if it is

Yes Next step

No Change sensor

Next step

1MΩ.

Check if there is open circuit or short circuit to ground

or to power supply between circuit of knock sensor

joint No.1, No.2 and ECU pin No.19, No. 20

Replace the knock sensor according to the regulation;

try running the vehicle and make the engine speed

exceed 2200rpm. Check if the DTC P0325 will appear

again.

Yes

No To step No.2

Yes Diagnosis help

Repair or replace

the cable3

Check if it is a

occasional fault

DTC: P0335 Crank shaft position sensor signal failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Take off the speed sensor joint from the cable; check

ignition switch to “OFF”

Yes Next step

Next step

the resistance value by multimeter between speed

sensor connector No.2and No.3 and observe if it is

No Replace sensor

around 770-950MΩwhen it is 20℃

Check if there is open circuit or short circuit to ground

or to power supply between circuit of speed sensor

joint No.2, No.3 and ECU pin No.34, No. 15

Check the flywheel signal disc if it is in good

conditions.

Yes

No Next step

Yes Diagnosis help

Repair or replace

the cable3

Replace signal

disc

DTC: P0336 Crank shaft position sensor signal unreasonable failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put

the ignition switch to “OFF”

Take off the speed sensor joint from the cable; check

Next step

Yes Next step

the resistance value by multimeter between speed

sensor connector No.2and No.3 and observe if it is

No Replace sensor

around 770-950MΩwhen it is 20℃

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Check if there is open circuit or short circuit to

ground or to power supply between circuit of speed

sensor joint pin No.2, No.3 and ECU pin No.34, No.

Check the flywheel signal disc if it is in good

conditions.

Yes

Repair or replace the

cable

No Next step

Yes Diagnosis help

No Replace signal disc

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0340 Phase sensor signal failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the phase sensor joint from the cable; check the

voltage value by multimeter between phase sensor joint pin

No.3 and No.1; and observe if it is around 12V.

Check if there is open circuit or short circuit to ground

between circuit of phase sensor joint pin No.3 and main

relay pin No.87; check if there is bad contact of phase

sensor connector No.1.

Next step

Yes To step No.4

No Next step

Repair or

Yes

replace the

cable

No Next step

Check the voltage if it is around 9.9V between phase sensor

joint pin No.2 and power supply cathode.

Check if there is open circuit or short circuit to power

supply or to ground between phase sensor joint pin No.2

and ECU pin No.79.

Yes To step 6

No Next step

Yes

Repair or

replace cable5

No Next step

Yes Diagnosis help

6 Check the camshaft signal disc if it is in good conditions.

Replace signal

disc

DTC: P0342 Much lower voltage of the phase sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the phase sensor joint from the cable; check the

voltage value by multimeter between phase sensor joint pin

No.3 and No.1; and observe if it is around 12V.

Check if there is open circuit or short circuit to ground

between circuit of phase sensor joint pin No.3 and main

relay pin No.87; check if there is bad contact of phase

sensor connector No.1.

Next step

Yes To step No.4

No Next step

Repair or

Yes

replace the

cable

No Next step

Check the voltage if it is around 9.9V between phase sensor

joint pin No.2 and power supply cathode.

Check if there is open circuit or short circuit to power

supply or to ground between the circuit of phase sensor

joint pin No.2 and ECU pin No.79.

6 Check the camshaft signal disc if it is in good conditions.

Yes To step 6

No Next step

Yes

Repair or

replace cable

No Next step

Yes Diagnosis help

Replace signal

disc

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0343 Much higher voltage of the phase sensor

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the phase sensor joint from the cable; check

the voltage value by multimeter between phase sensor

joint pin No.3 and No.1; and observe if it is around

Yes To step No.4

No Next step

Next step

12V.

Check if there is open circuit or short circuit to ground

between circuit of phase sensor joint pin No.3 and main

Yes

Repair or replace

the cable

relay pin No.87; check if there is bad contact of phase

sensor connector No.1.

Check the voltage if it is around 9.9V between phase

sensor joint pin No.2 and power supply cathode.

No Next step

Yes To step 6

No Next step

Check if there is open circuit or short circuit to power

supply or to ground between the circuit of phase sensor

joint pin No.2 and ECU pin No.79.

Check the camshaft signal disc if it is in good

conditions.

Yes

No Next step

Yes Diagnosis help

Repair or replace

cable

Replace signal

disc

DTC: P0443 Canister control valve drive grade control circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the canister control valve joint from the cable;

check the voltage value by multimeter between this

joint pin No.1 and power supply cathode; and observe

Yes To step No.4

No Next step

Next step

if it is around 12V.

Check if there is open circuit or short circuit to ground

of the canister control valve power supply ends circuit.

Yes

Repair or replace

the cable3

No To step No.2

Check the resistance value if it is around 22-30Ωwhen

Yes Next step

it is 20℃ between canister control valve pin No.1 and

pin No.2.

Check the voltage if it is around 3.7V between canister

control valve joint pin No.1 and power supply cathode.

Check if there is open circuit between the circuit of

canister joint pin No.2 and ECU pin No. 46.

No Replace the valve

Yes Diagnosis help

No Next step

Yes

Repair or replace

cable6

No Diagnosis help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0444 Much lower voltage of canister control valve drive grade control circuit

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the canister control valve joint from the cable;

check the voltage value by multimeter between this

joint pin No.1 and power supply cathode; and observe

Yes To step No.4

No Next step

Next step

if it is around 12V.

Repair or

Check if there is open circuit or short circuit to ground

of the canister control valve power supply ends circuit.

Yes

replace the

cable

No To step No.2

Check the resistance value if it is around 22-30Ω when

Yes Next step

it is 20℃ between canister control valve pin No.1 and

pin No.2.

Check the voltage by the multimeter if it is around

3.7V between canister control valve joint pin No.1 and power supply cathode.

Check if there is short circuit to ground between the

circuit of canister joint pin No.2 and ECU pin No. 46.

Yes Diagnosis help

No Next step

Yes

Replace the

valve

Repair or

replace cable6

No Diagnosis help

DTC: P0445 Much higher voltage of canister control valve drives grade control circuit

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”

Take off the canister control valve joint from the cable;

check the voltage value by multimeter between this joint

pin No.1 and power supply cathode; and observe if it is

Next step

Yes To step No.4

No Next step

around 12V.

Check if there is open circuit or short circuit to ground of

the canister control valve power supply ends circuit.

Yes

Repair or replace

the cable3

No To step No.2

Check the resistance value if it is around 22-30Ωwhen it

Yes Next step

is 20℃ between canister control valve pin No.1 and pin

No.2.

Check the voltage by the multimeter if it is around 3.7V

between canister control valve joint pin No.1 and power

supply cathode.

Check if there is short circuit to power supply between

the circuit of canister joint pin No.2 and ECU pin No. 46.

Replace the

valve

Yes Diagnosis help

No Next step

Yes

Repair or replace

cable

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

No Diagnosis help

DTC: P0480 Air conditioner condenser cooling fan relay control circuit failure

No. Operating steps Result

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Take off the air conditioner condenser cooling fan relay;

put the ignition switch to “ON”position, and check the

voltage value by multimeter between this relay power

supply end that is relay pin No.30, No.85 and power

Yes

No Next step

supply cathode if it is around 12V.

Check if there is open circuit or short circuit to ground of

Yes

the air conditioner cooling fan relay power supply end

circuit.

Check the voltage by the multimeter if it is around 3.7V

between air conditioner condenser cooling fan relay

Yes

control ends that is relay pin No.86 and power supply

cathode.

Check if there is open circuit or short circuit to power

No Next step

Yes

supply or to ground between the circuit of relay control

end pin No.86 and ECU pin No. 50.

Follow up

steps

Next step

To step

No.4

Repair or

replace the

cable3

To step

No.2

Replace

relay

Repair or

replace

cable5

Diagnosis

help

DTC: P0500 Unreasonable failure of speed signal

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Next step

Check and

If it is a vehicle with ABS, please check if there is

ABS DTC.

Yes

repair ABS

system

No Next step

Yes Next step

3 Check if the speedometer finger works normally.

Check the

speedometer

line

Yes Next step

4 Check if the speed sensor works normally.

5 Check if there is open circuit or short circuit to power

Yes Repair or

Replace speed

sensor

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

replace cablesupply or to ground between the circuit of speed

sensor and ECU pin No. 59.

No Diagnosis help

DTC: P0506 Rotating speed of idle speed is lower than target idle speed

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Next step

Yes Next step

Check if the throttle valve adjusting screw, accelerator

cable and throttle valve working in good conditions.

Carry out the

necessary repair and

maintenance

Yes Next step

Carry out the

3 Check if the idle speed regulator works in good conditions.

necessary repair and

maintenance

E, check if the pressure of the fuel supplying system is too

low

F, check if the injector is jammed

G, check if the exhaust system is not straightway

Yes Next step

Replace speed

sensor

DTC: P0507 Rotating speed of idle speed is higher than target idle speed

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”

Next step

Yes Next step

Check if the throttle valve adjusting screw, accelerator

cable and throttle valve working in good conditions.

Carry out the

necessary repair

and

maintenance

Yes Next step

Carry out the

3 Check if the idle speed regulator works in good conditions.

necessary repair

and

maintenance

A, check if the system is leaking;

C, check if the pressure of fuel supplying system is too

B, check if the injector is leaking;

Yes

high

Carry out the

necessary repair

and

maintenance

No Diagnosis help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0508 Idle speed regulator control circuit voltage is too low

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Take off the idle regulator joint and Check the resistance

value between idle speed regulator pin A and pin D, pin B

and pin C if it is around 53±5.3Ω when it is 20℃.

Next step

Yes Next step

Replace step

motor

Check if there is short circuit to ground between the circuits

of idle speed regulator joint pin A, B, C, D and ECU pin

No. 65, No.66, No.67. No.64.

Yes

No Diagnosis help

Repair or

replace cable3

DTC: P0509 Idle speed regulator control circuit voltage is too high

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Take off the idle regulator joint and check the resistance

Next step

Yes Next step

value by multimeter separately between idle speed regulator

pin Aand pin D, pin B and pin C if it is around 53±5.3Ω

when it is 20℃.

Check using multimeter separately if there is short circuit to

power supply between the circuits of idle speed regulator

Yes

Replace step

motor

Repair or

replace cable

joint pin A, B, C, D and ECU pin No. 65, No.66, No.67.

No.64.

No Diagnosis help

DTC: P0511 Idle speed regulator control circuit failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Take off the idle regulator joint and check the resistance

Next step

Yes Next step

value by multimeter separately between idle speed

regulator pin A and pin D, pin B and pin C if it is around

53±5.3Ω when it is 20℃.

Check using multimeter separately if there is open circuit

between the circuits of idle speed regulator joint pin A, B,

C, D and ECU pin No. 65, No.66, No.67. No.64.

Yes

Replace step

motor

Repair or

replace cable3

No Diagnosis help

DTC: P0560 System voltage signal unreasonable

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Next step

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

Check the accumulator voltage by multimeter if it is around

12V.

Check if there is open circuit or short circuit to ground

between the circuits of ECU pin No.44, No.45, No.63 and

main relay pin No.87.

Start the engine and check if the entire generator recharging

voltage is around 9-16V at the different engine speed.

Check the engine cable harness contact position if it is in

good conditions.

Yes Next step

Yes

Replace

accumulator

Repair or

replace cable3

No Next step

Yes Next step

Replace

generator

Yes Diagnosis help

Repair or

replace cable

DTC: P0562 System voltage is too low

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Check the accumulator voltage by the multimeter and

observe if it is around 12V.

Check if the resistance is over big between the circuits of ECU pin No.44, No.45, No.63 and main relay pin No.87.

Next step

Yes Next step

Yes

Replace

accumulator

Repair or

replace cable3

No Next step

Start the engine and check if the entire generator recharging

voltage is around 9-16V at the different engine speed.

Check the engine cable harness contact position if it is in

good conditions.

Yes Next step

Replace

generator

Yes Diagnosis help

Repair or

replace cable

DTC: P0563 System voltage is too high

No. Operating steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Check the accumulator voltage by the multimeter and

observe if it is around 12V.

Start the engine and check if the entire generator

recharging voltage is around 9-16V at the different engine

speed.

Check the engine cable harness contact position if it is in

good conditions.

Resu

Follow up steps

Next step

Yes Next step

Replace

accumulator

Yes Next step

No Replace generator

Yes Diagnosis help

No Repair or replace

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

cable

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0601 ECU testing code failure

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

Clean up the DTC and check the failure once again if it

ignition switch to “ON”.

is a steady failure.

Yes Next step

Next step

System if

correct

3 Replace ECU Finish

DTC: P0602 ECU diagnosis data ID code failure

No. Operating steps Result

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Clean up the DTC and check the failure once again if it is

a steady failure.

Yes Next step

3 Replace ECU Finish

DTC: P0645 Air conditioner compressor relay control circuit failure

No. Operating steps Result

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Take off air conditioner compressor relay; put ignition

switch to “ON”; check the voltage value between relay

Yes

power supply ends that relay pin No.30, No.85 and

power cathode and observe if it is around 12V.

Check if there is open circuit or short circuit to ground

No Next step

Yes

of the relay power supplying ends circuit.

Check the voltage value by the multimeter between air

conditioner compressor relay control ends that is relay

Yes

pin No.86 and power cathode and observe if it is around

3.7V.

Check if there is open circuit between the circuit of air

conditioner compressor relay control ends that is relay

No Next step

Yes

pin No.86 and ECU pin No.70.

Follow up

steps

Next step

System if

correct

Follow up

steps

Next step

To step

No.4

Repair or

replace

cable3

To step

No.2

Replace

relay

Repair or

replace

cable

Diagnosis

help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P0646 Much lower voltage of air conditioner compressor relay control circuit

No. Operating steps Result Follow up steps

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Take off air conditioner compressor relay; put ignition

switch to “ON”; check the voltage value between relay

power supply ends that relay pin No.30, No.85 and

Next step

Yes To step No.4

No Next step

power cathode and observe if it is around 12V.

Check if there is open circuit or short circuit to ground of

the relay power supplying ends circuit.

Yes

Repair or

replace cable

No To step No.2

Check the voltage value by the multimeter between air

conditioner compressor relay control ends that is relay

pin No.86 and power cathode and observe if it is around

Yes Replace relay

No Next step

3.7V.

Check if there is short circuit to ground between the

circuit of air conditioner compressor relay control ends

that is relay pin No.86 and ECU pin No.70.

Yes

No Diagnosis help

Repair or

replace cable5

DTC: P0647 Much higher voltage of air conditioner compressor relay control circuit

No. Operating steps Result

Connect the diagnostic tester and commutator, put the

ignition switch to “OFF”.

Take off air conditioner compressor relay; put ignition

switch to “ON”; check the voltage value between relay

power supply ends that relay pin No.30, No.85 and

Yes To step No.4

No Next step

Follow up

steps

Next step

power cathode and observe if it is around 12V.

Check if there is open circuit or short circuit to ground of

the relay power supplying ends circuit.

Yes

Repair or

replace cable

No To step No.2

Check the voltage value by the multimeter between air

conditioner compressor relay control ends that is relay

pin No.86 and power cathode and observe if it is around

Yes Replace relay

No Next step

3.7V.

Check if there is short circuit to power supply between

the circuit of air conditioner compressor relay control

ends that is relay pin No.86 and ECU pin No.70.

Yes

Repair or

replace cable5

Diagnosis

help

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

DTC: P1651 Trouble light control circuit failure

No. Operating steps Result

Connect the diagnostic tester and commutator, put the

ignition switch to “ON”.

Carry out action test to engine trouble light by using

diagnostic meter “actuator action test”item; and observe

the indicator if it is always at the status of extinguishing or

Yes Next step

lighting on.

Check if there is open circuit or short circuit to ground of

the engine trouble light power supplying circuit.

Yes

No Next step

Check if there is open circuit or short circuit to power

supply or short circuit to ground between the circuit of

engine trouble light control ends and ECU pin No. 28.

Yes

5. TYPICAL FAILURE AND ITS DIAGNOSIS FLOW

5.1 EXPLANATION

Follow up

steps

Next step

System is

correct

Repair or

replace cable

Repair or

replace cable

Diagnosis

help

Carry out the primary inspection before start the diagnosing according to the engine failure phenomenon.

1) Make sure the engine trouble light is working properly;

2) Make sure that there is no failure information record checked by diagnostic meter;

3) Make sure that the failure phenomenon exists according to the customers’complaints, and confirm the conditions causing the failure.

Then carry out the exterior inspection:

（1）

（2）

（3）

（4）

Check if there is any fuel pipe is leaking;

Check if the vacuum pipe is broken, kinked up or linked correctly;

Check if the air intake pipe is jammed, leaking, staved or damaged;

Check the high voltage line of ignition system if it is broken or aging and if the

（5）

ignition order is correct;

Check the cable grounding place if it is clean and fastness;

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

（6）

Check the sensor and actuator joint if it is loosening or bad contact.

Important notice: if the above phenomenon is appeared, you should repair the above the failure at first otherwise it will influence the later service.

Diagnosis help:1 Confirm there is no engine failure record;

2 Confirm that the failure exists before the customer complaints; 3 Inspect the engine according to the above steps and find nothing wrong; 4 During the service please do not ignore the influence from vehicle

maintenance, cylinder pressure, mechanical ignition timing and fuel conditions;

5 Replace ECU and carry out test. If the failure is deleted, the failure is in

ECU; if the failure can not be deleted, replace back to the original ECU and repeat the flow and check and repair it again.

5.2 TYPICAL FAILURE DIAGNOSIS FLOW

1. The engine does not rotate or rotate slowly when it is started

The normal failure component: 1) accumulator; 2) starting motor; 3) cable or ignition switch; 4) mechanical part of the engine.

The general diagnosis flow:

No. Operating steps Result Follow up steps

Check the voltage value between the two wiring terminals

of the accumulator by multimeter; check if it is around

8-12V when the engine is starting.

Put the ignition switch at start position, checking the anode

terminal of starting motor by multimeter and observe the

voltage if it is above 8V.

Yes Next step

Replace

accumulator

Yes Next step

Repair or

replace cable

Repair or

Disassemble the starting motor and check its working

conditions. Check if there is open circuit or jammed by

Yes

replace starting

motor

poor lubricating.

No Next step

If the failure is happened in winter time, check if it is

because of the wrong engine lubricant and gearbox oil

Yes

causes the big resistance of the starting motor.

Change to

correct

lubricant

No Next step

Repair the

Check the mechanical resistance inside of the engine if it is

too big causes the starting motor can not rotate or rotate

slowly.

Yes

engine inside

resistance5

Repeat the

above steps

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

2. The engine can draw rotating but can not start successfully when it is started.

General failure component: 1) no fuel in fuel tank; 2) fuel pump; 3) speed sensor; 4) ignition coil; 5) engine mechanical part.

Diagnosis flow:

No. Operating steps Result Follow up steps

Connect the fuel pressure meter ( connecting point is

Yes Next step

the front end of fuel distributing pipe assembly fuel

intake pipe); starting the engine by starter and check

fuel pressure if it is around 260kpa; take off the

vacuum pipe from fuel pressure regulator check the

Repair the fuel

supplying

system

fuel pressure if it is around 300kpa.

Connect EFI diagnostic meter; observe “engine speed”

data item and start the engine and check if there is

rotation speed signal is output.

Pull off one of the cylinder separating line and take off

this cylinder injector joint and connect spark plug to it;

keep the spark electrode around 5mm away from

engine body; start the engine by starter and check if

there is blue and white high pressure fire.

4 Check the pressure of each engine cylinder; check if

there is engine cylinder insufficient pressure.

Check if the power supply to ECU pin No.12, 13, 44,

45, 63 is correct; check if the pin armature of No. 3,

51, 53, 61, 80 are working correctly.

Yes Next step

Repair the

sensor cable

Yes Next step

Repair the

ignition system

Eliminate

Yes

engine

mechanical

failure

No Next step

Yes Diagnosis help

Check the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

3. It is hard to start the heating car.

General failure component: 1) water inside of fuel; 2) fuel pump; 3) coolant temperature sensor; 4) fuel pressure regulator vacuum pipe; 5) ignition coil.

General diagnostic flow

No. Operating steps Result

Connect the fuel pressure meter ( connecting point is the

Yes Next step

front end of fuel distributing pipe assembly fuel intake

pipe); starting the engine and check fuel pressure at idle

speed if it is around 260kpa; take off the vacuum pipe

from fuel pressure regulator check the fuel pressure if it

is around 300kpa.

Pull off one of the cylinder separating line and connect

spark plug to it; keep the spark electrode around 5mm

away from engine body; start the engine and check if

Yes Next step

there is blue and white high pressure fire.

Take off the coolant temperature sensor joint and start

the engine; observe if the engine can be started

Yes

successfully. (or serial connecting a 300Ωresistance at

the joint of coolant temperature sensor; observe if we

can start the engine)

Check if there if loosen or leaking of the fuel pressure

regulator vacuum pipe..

No Next step

Yes

No Next step

Follow up

steps

Repair the

fuel supplying

system

Repair the

ignition

system

Repair circuit

or replace

sensor

Repair or

replace

Check fuel conditions and check if the failure is

appeared after the fuel refilling

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and

No.63 if it is in right conditions; check pin armature of

No.3, 51, 53, 61 and No.80 if it is in right conditions.

Yes Change fuel

Yes

Diagnosis

help

Diagnosis

help

Check

correspond

circuit

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

4. It’s hard to start the cold car.

General failure component: 1), water in the fuel; 2), fuel pump; 3), coolant temperature sensor; 4), injector; 5), ignition coil; 6), throttle valve and idle speed by pass port; 7), engine mechanical part.

General diagnosis flow:

No. Operating steps Result Follow up steps

Connect the fuel pressure meter ( connecting point is the

Yes Next step

front end of fuel distributing pipe assembly fuel intake

pipe); start the engine and check fuel pressure at idle

speed if it is around 260kpa; take off the vacuum pipe

from fuel pressure regulator check the fuel pressure if it

Repair the fuel

supplying system

is around 300kpa.

Pull off one of the cylinder separating line and connect

spark plug to it; keep the spark electrode around 5mm

away from engine body; start the engine and check if

there is blue and white high pressure fire.

Take off the coolant temperature sensor joint and start the

engine; observe if the engine can be started successfully.

Yes Next step

Yes

Check and repair

ignition system

Repair circuit or

replace sensor

(or serial connecting a 2500Ωresistance at the joint of

coolant temperature sensor; observe if we can start the

No Next step

engine)

Clean throttle

Step on the accelerator slightly and observe if it is easy to

be started

Yes

valve and idle

speed air port

No Next step

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it

is leaking or jammed.

Check fuel conditions and check if the failure is appeared

Check pressure conditions of every cylinder and observe

after the fuel refilling

if there is insufficient pressure

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and

No.63 if it is in right conditions; check pin armature of

No.3, 51, 53, 61 and No.80 if it is in right conditions.

Yes Replace the part

No Next step

Yes Change fuel

No Next step

Yes Trouble shoot

No Next step

Yes Diagnosis help

Check correspond

circuit

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

5. Normal engine speed but hard to start at any time.

General failure component: 1), water in fuel; 2), fuel pump; 3), coolant temperature sensor; 4), injector; 5), ignition coil; 6), throttle valve and idle speed by pass port; 7), air intake port; 8), ignition timing; 9), spark plug; 10), engine mechanical part.

General diagnosis flow:

No. Operating steps Result Follow up steps

Check the air cleaner if it is jammed; check the air

intake port if it is leaking.

Yes

Repair the air

intake system

No Next step

Connect the fuel pressure meter ( connecting point is

Yes Next step

the front end of fuel distributing pipe assembly fuel

intake pipe); start the engine and check fuel pressure

at idle speed if it is around 260kpa; take off the

vacuum pipe from fuel pressure regulator check the

Repair the fuel

supplying system

fuel pressure if it is around 300kpa.

Pull off one of the cylinder separating line and connect

spark plug to it; keep the spark electrode around 5mm

away from engine body; start the engine and check if

there is blue and white high pressure fire.

Check spark plugs in every cylinder and observe its

type and clearance if it is accord with the regulation.

Yes Next step

Check and repair

ignition system

Yes Next step

No Adjust or replace

Take off the coolant temperature sensor joint and start

the engine; observe if the engine can be started

successfully.

Step on the accelerator slightly and observe if it is

easy to be started easily.

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if

it is leaking or jammed.

Check fuel conditions and check if the failure is

appeared after the fuel refilling

Check pressure conditions of every cylinder and

observe if there is insufficient pressure

Check the engine ignition order and ignition timing if

it is accord with the regulation.

Yes

Repair circuit or

replace sensor5

No Next step

Clean throttle

Yes

valve and idle

speed air port

No Next step

Yes Replace the part

No Next step

Yes Change fuel

No Next step

Yes Trouble shoot

No Next step

Yes Next step

Repair the

ignition timing

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

6. Regular starts but the idle speed is not steady at any time.

General failure component: 1), water in fuel; 2), injector; 3), spark plug; 4), throttle valve and idle speed by pass port; 5), air intake port; 6), idle speed regulator; 7), ignition timing; 8), spark plug; 9), engine mechanical.

General diagnosis flow:

No. Operating steps Result Follow up steps

Check the air cleaner if it is jammed; check the air intake

port if it is leaking.

Yes

Repair the air intake system

No Next step

2 Check idle speed regulator if it is partial blocked

Yes

Clean or

replace

No Next step

Check spark plugs in every cylinder and observe its type

and clearance if it is accord with the regulation.

Check the throttle valve and idle speed by pass if there is

carbon deposition.

Yes Next step

Adjust or

replace

Yes Cleaning

No Next step

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it is

leaking or jammed.

Check fuel conditions and check if the failure is appeared

Check pressure conditions of every cylinder and observe if

there is big pressure difference between the cylinders.

Check the engine ignition order and ignition timing if it is

after the fuel refilling

accord with the regulation.

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes Replace part

No Next step

Yes Change fuel

No Next step

Yes Trouble shoot

No Next step

Yes Next step

Repair the

ignition timing

Yes Diagnosis help

Repair the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

7. Regular starts but the idle speed is not steady during engine heating.

General failure component: 1), water in fuel; 2), coolant temperature sensor; 3), spark plug; 4), throttle valve and idle speed by pass port; 5), air intake port; 6), idle speed regulator; 7), engine mechanical.

General diagnosis flow:

No. Operating steps Result Follow up steps

Check the air cleaner if it is jammed; check the air

intake port if it is leaking.

Yes

Repair the air intake system

No Next step

Check spark plugs in every cylinder and observe its

type and clearance if it is accord with the regulation.

Disassemble the idle speed regulator and check the throttle valve and idle speed by pass port if there is

carbon deposition

Pull off coolant temperature sensor joint and start the

engine; observe the engine if it is idle speed unsteady

during warming up the engine.

Yes Next step

No Adjust or replace

Yes

Cleaning the

related parts3

No Next step

Yes

Repair the line or

replace sensor

No Next step

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe

if it is leaking or jammed or overflowing.

Check fuel conditions and check if the failure is

appeared after the fuel refilling

Check pressure conditions of every cylinder and

observe if there is big pressure difference between

the cylinders.

Connect EFI system adaptor, turn on the ignition

Yes Replace part

No Next step

Yes Change fuel

No Next step

Yes Trouble shoot

No Next step

Yes Diagnosis help

switch; check the power supply of pin No.12, 13, 44,

45 and No.63 if it is in right conditions; check pin

armature of No.3, 51, 53, 61 and No.80 if it is in

right conditions.

Repair the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

8. Regular starts but idle speed is not steady after the engine heating.

General failure component: 1), water in fuel; 2), coolant temperature sensor; 3), spark plug; 4),throttle valve and idle by pass port; 5), air intake port; 6), idle speed regulator;

7), engine mechanical part.

General diagnosis flow:

No. Operating steps Result Follow up steps

Check the air cleaner if it is jammed; check the air intake

port if it is leaking.

Yes

Repair the air intake system

No Next step

Check spark plugs in every cylinder and observe its type

and clearance if it is accord with the regulation.

Disassemble the idle speed regulator and check the throttle

valve and idle speed by pass port if there is carbon

deposition

Yes Next step

Yes

Adjust or

replace

Cleaning the

related parts3

No Next step

Repair the line

Pull off coolant temperature sensor joint and start the

engine; observe the engine if it is idle speed unsteady

Yes

or replace

sensor

during warming up the engine.

No Next step

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it is

leaking or jammed or overflowing.

Check fuel conditions and check if the failure is appeared

just after the fuel refilling

Check pressure conditions of every cylinder and observe if

there is big pressure difference between the cylinders.

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes Replace part

No Next step

Yes Change fuel

No Next step

Yes Trouble shoot

No Next step

Yes Diagnosis help

Repair the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

9. Regular starts but idle speed is not steady or dying out when there is partial loading.

General failure component: 1) air conditioner system; 2) idle speed regulator; 3) injector.

General diagnosis flow:

No. Operating steps Result Follow up steps

Disassemble the idle speed regulator and check the

throttle valve and idle speed by pass port if there is

carbon deposition.

Observe if the engine output power increased when

Yes

No Next step

Yes To step No.4

Cleaning the

related parts1

the air conditioner is switched on, that is using EFI

system diagnosis meter observing ignition angle of

advance, fuel injection pulse width and changes of air

No Next step

intake flow.

Connect EFI system adaptor; break connecting line of

ECU pin No.75; check the cable end if it is up level

signal when the air conditioner is switched on.

Yes Next step

Repair air

conditioning

system

Check air conditioning system pressure; check the

compressor solenoid clutch and air conditioner

compressor pump fuel conditions and check if it is

working correctly.

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if

it is leaking or jammed or overflowing.

Connect EFI system adaptor, turn on the ignition

Yes Next step

Repair the air

conditioning sys.

Yes Replace fault part

No Next step

Yes Diagnosis help

switch; check the power supply of pin No.12, 13, 44,

45 and No.63 if it is in right conditions; check pin

armature of No.3, 51, 53, 61 and No.80 if it is in right

conditions.

Repair the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

10. Regular starts with high idle speed.

General failure component: 1) throttle valve and idle speed by pass port; 2) vacuum pipe; 3) idle speed regulator; 4) coolant temperature sensor; 5) ignition timing.

General diagnosis flow:

No. Operating steps Result Follow up steps

1 Check accelerator cable if it is blocked or over tightening

Yes Adjust

No Next step

Repair the air

Check the air intake system and its connecting vacuum pipe

if it is leaking.

Yes

in taking

system

No Next step

Disassemble the idle speed regulator and check the throttle

valve and idle speed by pass port if there is carbon

deposition

Take off the coolant temperature sensor joint; start the

engine and observe if it has high idle speed.

Check the engine ignition timing if it is accord with the

regulations.

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes

Clean related

part3

No Next step

Yes

Repair line or

replace sensor

No Next step

Yes Next step

Repair the

ignition timing

Yes Diagnosis help

Repair the

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

11. Low engine speed or dying out exists when it is accelerated.

General failure component: 1) water in fuel; 2) air intake pressure sensor and throttle position sensor; 3) spark plug; 4) throttle valve and idle speed by pass port; 5) air intake port; 6) idle speed regulator; 7) injector; 8) ignition timing; 9) exhaust pipe.

General diagnosis flow:

No. Operating steps Result Follow up steps

1 Check the air cleaner if it is jammed.

Yes

Repair the air intake system

No Next step

Connect the fuel pressure meter ( connecting point is the

Yes Next step

front end of fuel distributing pipe assembly fuel intake

pipe); start the engine and check fuel pressure at idle speed

if it is around 260kpa; take off the vacuum pipe from fuel

pressure regulator check the fuel pressure if it is around

Repair the fuel

supplying

system

300kpa.

Check spark plugs in every cylinder and observe its type

and clearance if it is accord with the regulation.

Disassemble idle speed regulator and check throttle valve,

idle speed regulator and idle speed by pass port if there is

carbon deposition.

Yes Next step

Yes

Adjust or

replace

Clean related

part

No Next step

Inspect air intake pressure sensor, throttle position sensor

and its line if it is working correctly.

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it is

leaking or jammed.

Check fuel conditions and check if the failure is appeared

after the fuel refilling

Check the engine ignition order and ignition timing if it is

accord with the regulation.

9 Check the exhaust pipe if the air exhausting is smooth

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes Next step

Yes

Repair line or

replace sensor

Replace fault

part6

No Next step

Yes Replace fuel

No Next step

Yes Next step

Repair ignition

timing

Yes Next step

Repair or

replace exhaust

pipe

Yes Diagnosis help

Repair

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

12. React slowly when it is accelerated.

General diagnosis flow:

No. Operating steps Result Follow up steps

1 Check the air cleaner if it is jammed.

Yes

Repair the air intake system

No Next step

Connect the fuel pressure meter ( connecting point is the

Yes Next step

front end of fuel distributing pipe assembly fuel intake

pipe); start the engine and check fuel pressure at idle speed

if it is around 260kpa; take off the vacuum pipe from fuel

pressure regulator check the fuel pressure if it is around

Repair the fuel

supplying

system

300kpa.

Check spark plugs in every cylinder and observe its type

and clearance if it is accord with the regulation.

Disassemble idle speed regulator and check throttle valve,

idle speed regulator and idle speed by pass port if there is

carbon deposition.

Yes Next step

Yes

Adjust or

replace

Clean related

part

No Next step

Inspect air intake pressure sensor, throttle position sensor

and its line if it is working correctly.

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it is

leaking or jammed.

Check fuel conditions and check if the failure is appeared

after the fuel refilling

Check the engine ignition order and ignition timing if it is

accord with the regulation.

9 Check the exhaust pipe if the air exhausting is smooth

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes Next step

Yes

Repair line or

replace sensor

Replace fault

part6

No Next step

Yes Replace fuel

No Next step

Yes Next step

Repair ignition

timing

Yes Next step

Repair or

replace exhaust

pipe

Yes Diagnosis help

Repair

corresponding

line

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

13. The performance is poor when it is accelerated.

General failure component:1) water in fuel; 2) air intake pressure sensor and throttle position sensor; 3) spark plug; 4) ignition coil; 5) throttle valve and idle speed by pass port; 6) air intake port;7) idle speed regulator; 8) injector; 9) ignition timing; 10) exhaust pipe.

General diagnosis flow:

No. Operating steps Result

Check if there are failures like clutch skidding, low tyre

pressure, brake dragging, wrong tyre size, and wrong four

Yes Repair

wheel positioning etc..

Yes

No Next step

Connect the fuel pressure meter ( connecting point is the

Yes Next step

front end of fuel distributing pipe assembly fuel intake

pipe); start the engine and check fuel pressure at idle speed

if it is around 260kpa; take off the vacuum pipe from fuel

pressure regulator check the fuel pressure if it is around

300kpa.

Pull off one of the cylinder separating line and connect

spark plug to it; keep the spark electrode around 5mm away

from engine body; start the engine and check the high

Yes Next step

pressure fire strength if it is regular.

Check spark plugs in every cylinder and observe its type and

clearance if it is accord with the regulation.

Disassemble idle speed regulator and check throttle valve,

idle speed regulator and idle speed by pass port if there is

carbon deposition.

Inspect air intake pressure sensor, throttle position sensor

and its line if it is working correctly.

Disassemble the injector, check the injector using the

injector special cleaning analysis meter and observe if it is

leaking or jammed.

Check fuel conditions and check if the failure is appeared

after the fuel refilling

Yes Next step

Yes

No Next step

Yes Next step

Yes

No Next step

Yes Replace fuel

No Next step

Yes Next step

Check the engine ignition order and ignition timing if it is

accord with the regulation.

Follow up

steps

Next step

Repair the air intake system2 Check the air cleaner if it is jammed.

Repair the

fuel supplying

system

Repair

ignition

system

Adjust or

replace

Clean related

part6

Repair line or

replace sensor

Replace fault

part8

Repair

ignition

timing

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

11 Check the exhaust pipe if the air exhausting is smooth

Connect EFI system adaptor, turn on the ignition switch;

check the power supply of pin No.12, 13, 44, 45 and No.63

if it is in right conditions; check pin armature of No.3, 51,

53, 61 and No.80 if it is in right conditions.

Yes Next step

Repair or

replace

exhaust pipe

Yes

Diagnosis

help

Repair

corresponding

line

Chery Fora A21 2007 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual