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
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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
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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
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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
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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.
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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
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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.
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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
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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
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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;
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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
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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
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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
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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.
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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:
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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
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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
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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.
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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.
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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
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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.
21
Fuel Pump Relay
Electric Fuel Pump
Connect
Relay
Chart 3-10 Exterior Drawing Of Phase
Power Supply
Sensor
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