This manual was produced by the Yamaha Motor Company, Ltd. primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in
one manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha
vehicles should have a basic understanding of mechanics and the techniques to repair these types
of vehicles. Repair and maintenance work attempted by anyone without this knowledge is likely to
render the vehicle unsafe and unfit for use.
Yamaha Motor Company, Ltd. is continually striving to improve all of its models. Modifications and
significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and will appear in future editions of this manual where applicable.
NOTE:
@
Designs and specifications are subject to change without notice.
EAS00004
IMPORTANT MANUAL INFORMATION
Particularly important information is distinguished in this manual by the following.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
WARNING
CAUTION:
NOTE:
Failure to follow WARNING instructions could result in severe injury or death to
the motorcycle operator, a bystander or a person checking or repairing the
motorcycle.
A CAUTION indicates special precautions that must be taken to avoid damage
to the motorcycle.
A NOTE provides key information to make procedures easier or clearer.
EAS00007
HOW TO USE THIS MANUAL
This manual is intended as a handy, easy-to-read reference book for the mecha nic. Co mprehensive
explanations of all installation, removal, disassembly, assembly, repair and check procedures are
laid out with the individual steps in sequential order.
The manual is divided into chapters. An abbreviation and symbol in the upper right corner of
1
each page indicate the current chapter.
Refer to “SYMBOLS”.
Each chapter is divided into sections. The current section title is shown at the top of each page,
2
except in chapter 3 (“PERIODIC CHECKS AND ADJUSTMENTS”), where the sub-section title(s)
appears.
Sub-section titles appear in smaller print than the section title.
3
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of
4
each removal and disassembly section.
Numbers are given in the order of the jobs in the exploded diagram. A circled number indicates a
5
disassembly step.
Symbols indicate parts to be lubricated or replaced.
6
Refer to “SYMBOLS”.
A job instruction chart accompanies the exploded diagram, providing the order of jobs, names of
7
parts, notes in jobs, etc.
Jobs requiring more information (such as special tools and technical data) are described sequen-
8
tially.
12
GEN
SPEC
INFO
34
CHK
CHAS
ADJ
56
ENG
78
COOL
EAS00008
SYMBOLS
The following symbols are not relevant to
every vehicle.
Symbols 1 to 9 indicate the subject of each
chapter.
General information
1
Specifications
2
Periodic checks and adjustments
3
Chassis
4
Engine
5
Cooling system
6
Fuel injection system
7
Electrical system
8
Troubleshooting
9
FI
90
ELEC
–+
TRBL
SHTG
AB
CD
T
.
R
.
EFG
HIJ
Symbols 0 to G indicate the following.
Serviceable with engine mounted
0
Filling fluid
A
Lubricant
B
Special tool
C
Tightening torque
D
Wear limit, clearance
E
Engine speed
F
Electrical data
G
Symbols H to M in the exploded diagrams
indicate the types of lubricants and lubrication
points.
LS
G
M
M
New
E
KLM
B
NO
LT
Engine oil
H
Gear oil
I
Molybdenum disulfide oil
J
Wheel bearing grease
K
Lithium soap base grease
L
Molybdenum disulfide grease
M
Symbols N to O in the exploded diagrams
indicate the following.
®
Apply locking agent (LOCTITE
N
Replace the part
O
)
EAS00012
–+
Notice: This enhanced version has been prepared for persons who already own a copy of
the FJR Service Manual. The enhancements are distributed as freeware for the FJR
Owner's community. If you find them useful, please donate 5 or 10 units of your local
currency to a motorcycle charity or related event.
The vehicle identification number 1 is
stamped into the right side of the steering head
pipe.
EAS00018
MODEL CODE
The model code label 1 is affixed to the
frame. This information will be needed to order
spare parts.
GEN
INFO
1 - 1
GEN
FEATURES
FEATURES
OUTLINE
The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum air-fuel ratio in accordance with the engine operating conditions and the atmospheric temperature.
In the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the combustion chamber is created by the volume of the intake air and the fuel that is metered by the jet that
is used in the respective chamber.
Despite the same volume of intake air, the fuel volume requirement varies by the engine operating
conditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors that
meter the fuel through the use of jets have been provided with various auxiliary devices, so that an
optimum air-fuel ratio can be achieved to accommodate the constant changes in the operating conditions of the engine.
As the requirements for the engine to deliver more performance and cleaner exhaust gases
increase, it becomes necessary to control the air-fuel ratio in a more precise and finely tuned manner. To accommodate this need, this model has adopted an electronically controlled fuel injection
(FI) system, in place of the conventional carburetor system. This system can achieve an optimum
air-fuel ratio required by the engine at all times by using a microprocessor that regulates the fuel
injection volume according to the engine operating conditions detected by various sensors.
The adoption of the FI system has resulted in a highly precise fuel supply, improved engine
response, better fuel economy, and reduced exhaust emissions. Furthermore, the air induction system (AI system) has been placed under computer control together with the FI system in order to
realize cleaner exhaust gases.
INFO
Ignition coil
1
Air filter case
2
Intake temperature
3
sensor
Fuel delivery hose
4
Fuel tank
5
Fuel pump
6
Fuel return hose
7
Intake air pressure
8
sensor
Throttle position sensor
9
Fuel injector
0
sensor
O
2
A
Catalytic converter
B
Crankshaft position
C
sensor
Coolant temperature
D
sensor
1 - 2
Spark plug
E
Cylinder identifica-
F
tion sensor
Pressure regulator
G
Battery
H
ECU
I
Atmospheric pressure
J
sensor
Fuel injection system
K
relay
Engine trouble warn-
L
ing light
Lean angle cut-off
M
switch
Air cut-off valve
N
GEN
FEATURES
FI SYSTEM
The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the
2
fuel pressure that is applied to the injector at only 2.55 kg/cm
sure. Accordingly, when the energizing signal from the ECU energizes the injector, the fuel passage
opens, causing the fuel to be injected into the intake manifold only during the time the passage
remains open. Therefore, the longer the length of time the injector is energized (injection duration),
the greater the volume of fuel that is supplied. Conversely, the shorter the len gth of time the injector
is energized (injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from
the throttle position sensor, crankshaft position sensor, intake air pressure sensor, atmospheric
pressure sensor, intake temperature sensor, coolant temperature sensor, and O
ECU to determine the injection duration. The injection timing is determined through the signals from
the crankshaft position sensor and the cylinder identification sensor. As a result, the volume of fuel
that is required by the engine can be supplied at all times in accordance with the driving conditions.
Illustration is for reference only.
higher than the intake manifold pres-
INFO
2
sensor enable the
Fuel pump
1
Pressure regulator
2
Fuel injector
3
Throttle body
4
Intake temperature
5
sensor
#4
#3
Throttle position sen-
6
sor
Intake air pressure
7
sensor
ECU
8
Atmospheric pressure
9
sensor
#2
#1
Coolant temperature
0
sensor
sensor
O
2
A
Cylinder identification
B
sensor
Crankshaft position
C
sensor
Fuel system
È
Air system
É
Control system
Ê
1 - 3
GEN
FEATURES
Fuel control block
The fuel control block consists of the following main components:
ComponentFunction
Control blockECUTotal FI system control
Throttle bodyAir volume control
Pressure regulatorFuel pressure detection
Sensor blockIntake air pressure sensorIntake air pressure detection
Atmospheric pressure sensorAtmospheric pressure detection
Coolant temperature sensorCoolant temperature detection
Intake temperature sensorIntake temperature detection
Throttle position sensorThrottle angle detection
2
O
sensorGas emission O2 concentration detection
Cylinder identification sensorReference position detection
Crankshaft position sensorCrankshaft position detection and engine
RPM detection
Speed sensorSpeed detection
INFO
Actuator blockInjectorFuel injection
Fuel pumpFuel feed
Air Induction system, air cut valveInduction of secondary air
An FI warning light is provided on meter panel.
1 - 4
GEN
FEATURES
COMPONENTS
ECU (Electronic Control Unit)
The ECU is mounted underneath the seat, below the toolbox. The main fun ctio ns of th e ECU are
ignition control, fuel control, self-diagnosis, and load control.
• ECU’s internal construction and functions
The main components and functions of the ECU can be broadly divided into the following four
items:
A. Power supply circuit
The power supply circuit obtains power from the battery (12 V) to supply the power (5 V) that is
required for operating the ECU.
B. Input interface circuits
The input interface circuits convert the signals output by all the sensors into digital signals,
which can be processed by the CPU, and input them into the CPU.
C. CPU (Central Processing Unit)
The CPU determines the condition of the sensors in accordance with th e level of the signal that
is output by the respective sensor. Then, the signals are temporarily stored on the RAM in the
CPU. Based on those stored signals and the basic processing program on the ROM, the CPU
calculates the fuel injection duration, injection timing, and ignition timing, and then sends control commands to the respective output interface circuits.
D. Output interface circuits
The output interface circuits convert the control signals output by the CPU into actuating signals for the respective actuators in order to actuate them. They also output commands to the
indicator and relay output circuits as needed.
INFO
Hall sensor
signal
(for cylinder
identification)
Pickup coil signal
(for identifying the
crankshaft position)
Switches
Sensors
ECU
Input
interface circuit
Waveform
shaping circuit
Waveform
shaping circuit
Digital input circuit
A/D converter
input circuit
Battery
Power
supply
circuit
CPU
RAM/ROM
MEMORY
Output
interface circuit
Injector drive
output circuit
Ignition output circuit
Lamp drive
output circuit
Relay drive
output circuit
Injector
Ignition coil
Indicating lamp
Relay
1 - 5
GEN
FEATURES
• Ignition control
The ignition control function of the ECU controls the ignition timing and the duration of ignition
energizing. The ignition timing control uses the signals from the throttle position sensor (to detect
the angle of the throttle), and the crankshaft position sensor and speed sensor (to detect the
speed of the engine). This control establishes an ignition timing that suits the operating condition
of the engine through compensations made to the basic ignition timing control map. The ignition
energizing duration control establishes the energizing duration to suit the operating conditions by
calculating the energizing duration in accordance with the signal received from the crankshaft
position sensor and the battery voltage.
• Fuel control
The fuel control function of the ECU controls the injection timing and injection duration. The injection timing control controls the injection timing during the starting of the engine and the injection
timing during the normal operation of the engine, based on the signals received from the crankshaft position sensor and the cylinder identification sensor. The injection duration control determines the duration of injection based on the signals received from the atmospheric pressure
sensors, temperature sensors, and the position sensors, to which compensations are made to suit
various conditions such as the weather, atmospheric pressure, starting, acceleration, and deceleration.
• Load control
The ECU effects load control in the following manner:
1. Stopping the fuel pump and injectors when the motorcycle overturns
The ECU turns OFF the fuel injection system relay when the lean angle cut-off switch is tripped.
2. Operating the headlight illumination relay
On the model for Europe, the ECU causes the headlight relay 2 to output a constant ON signal,
provided that the main switch is ON. On the model for Australia, the ECU controls the headlight
relay 2 in accordance with the engine speed as required by the daytime illumination specification.
3. Operating the radiator fan motor in accordance with the coolant temperature
The ECU controls the radiator fan motor relay ON/OFF in accordance with the coolant temperature.
4. Operating the AI system solenoid valve
The ECU controls the energizing of the solenoid valve in accordance with the driving conditions.
• Self-diagnosis function
The ECU is equipped with a self-diagnosis function to ensure that the engine control system is
operating normally. The ECU mode functions include a diagnosis mode in addition to the normal
mode.
Normal mode
• To check for any blown bulbs, this mode illuminates a warning light while the main switch is
turned ON, and while the starter switch is being pressed.
• If the starting disable warning is activated, this mode alerts the rider by blinking the warning light
while the start switch is being pressed.
• If a malfunction occurs in the system, this mode provides an appropriate substitute characteristic
operation, and alerts the rider of the malfunction by illuminating a warning light. After the engine
is stopped, this mode displays a fault code on the clock LCD.
Diagnosis mode
• In this mode, a diagnostic code is input into the ECU through the operation of the operating
switch on the meter, and the ECU displays the values output by the sensors or actuates the
actuators in accordance with the diagnostic code. Whether the system is ope ratin g nor mally can
be checked by observing the illumination of the warning light, the values displayed on the meter,
or the actuating state of the actuators.
INFO
1 - 6
GEN
FEATURES
Fuel pump
The fuel pump, which is mounted in the fuel tank, draws the fuel directly from the tank and pumps it
to the injector.
A filter that is provided in the fuel pump prevents any debris in the fuel tank from entering the fuel
system downstream of the pump.
The pump consists of a pump unit, electric motor, filter, and valves.
The pump unit is a Wesco type rotary pump that is connected to the motor shaft.
A relief valve is provided to prevent the fuel pressure from rising abnormally if the fuel hose
becomes clogged. This valve opens when the fuel pressure at the discharge outlet reaches
between 440 and 640 kpa, and returns the fuel to the fuel tank.
INFO
Fuel filter
1
Fuel inlet strainer
2
Outlet
3
Fuel
È
1 - 7
GEN
FEATURES
Pressure regulator
It regulates the fuel pressure that is applied to the injectors th at are provid ed in the cylind ers in order
to maintain a constant pressure difference with the pressure in the intake manifold.
The fuel that is delivered by the fuel pump fills the fuel chamber through the fuel inlet of the regulator
and exerts pressure on the diaphragm in the direction for opening the valve.
A spring that is provided in the spring chamber exerts pressure on the diaphragm in the dire ction for
closing the valve, in contrast to the pressure of the fuel. Thus, the valve cannot open unless the fuel
pressure overcomes the spring force.
An intake vacuum is applied to the spring chamber via a pipe. When the pressure of the fuel
exceeds the sum of the intake vacuum and the spring force, the valve that is integra ted with the diaphragm opens, allowing the fuel to return from the fuel outlet to the fuel tank, via the fuel return
hose.
As a result, because the intake vacuum fluctuates in accordance with the changes in the operating
conditions in contrast to the constant volume of fuel supplied by the pump, the valve opening/closing pressure also changes to regulate the return fuel volume. Thus, the difference between the fuel
pressure and the intake manifold pressure remains constant at a prescribed pressure.
INFO
Spring chamber
1
Spring
2
Diaphragm
3
Fuel inlet
4
Fuel outlet
5
Fuel chamber
6
7
8
1 - 8
Valve
Intake manifold vacuum pressure
Spring pressure
È
Fuel pressure
É
Vacuum pressure
Ê
GEN
FEATURES
Fuel injector
Upon receiving injection signals from the ECU, the fuel injector injects fuel. In the normal state, the
core is pressed downward by the force of the spring, as illustrated. The needle that is integrated
with the bottom of the core keeps the fuel passage closed.
When the current flows to the coil in accordance with the signal from the ECU, the core is drawn
upward, allowing the flange that is integrated with the needle to move to the spacer. Since the distance of the movement of the needle is thus kept constant, the opening area of the fuel passage
also becomes constant. Because the pressure difference of the fuel to the intake manifold pressure
is kept constant by the pressure regulator, the fuel volume varies in proportion to the length of time
the coil is energized. The injector that has been recently adopted has a four-hole type injection orifice that enhances the atomization of fuel and improves combustion efficiency.
INFO
1
2
3
4
Fuel
Coil
Core
Spacer
5
6
7
Needle
Inject
Flange
1 - 9
GEN
FEATURES
Crankshaft position sensor
The crankshaft position sensor uses the signals of the pickup coil that is mounted on the right side
of the crankshaft. When the rotation of the pickup rotor that is attached to the crankshaft causes the
projections on the rotor to pass by the pickup coil, an electromotive force is generated in the coil.
The voltage of this force is then input into the ECU, which calculates the position of the crankshaft
and the speed of the engine. The ignition timing is then determined in accordance with the calculated data, in order to determine the corresponding injection timing. Based on the changes in the
time intervals of the signals generated by the pickup coil, the ECU calculates the ignition timing
advance to suit the operating conditions. The injection timing is also advanced in accordance with
the ignition timing in order to supply fuel to the engine at an optimal timing.
INFO
5˚
F7T556
180˚
W
5
J
180˚
180˚
180˚
Pickup rotor
1
Direction of rotation
È
#1 cylinder compression stroke, 5° BTDC
É
Pickup signal
Ê
Trigger pole
Ë
1 - 10
GEN
FEATURES
Cylinder identification sensor
The cylinder identification sensor is mounted on the exhaust head cover of the #4 cylinder. When
the exhaust cam of the #4 cylinder rotates and the lift of the cam passes by the sensor, the sensor
generates a signal and sends it to the ECU. Based on this signal and the signal from the crankshaft
position sensor, the ECU then actuates the injector of the cylinder that is currently in order to supply
fuel.
INFO
Cylinder identification
1
sensor
Cam
2
#1
#2
#4
#3
180˚
Cam lift
È
Crankshaft position
É
sensor signal
Cylinder identification
Ê
sensor signal
180˚
180˚
Cylinder firing order
Ë
#4 cam lobe onto
Ì
exhaust camshaft
Combustion
Í
180˚
Exhaust
Î
Injection
Ï
Intake
Ð
Compression
Ñ
Ignition
Ò
1 - 11
GEN
FEATURES
Throttle position sensor
The throttle position sensor measures the intake air volume by detecting the position of the throttle
valve. It detects the mechanical angle of the throttle valve through the positional relationship
between the moving contact that moves in unison with the throttle shaft and the resistor board. In
actual operation, the ECU supplies 5 V power to both ends of the resistor board and the voltage that
is output by the throttle position sensor is used to determine the angle of the throttle valve.
50
40
INFO
Moving contact
1
Resistor board
2
Spring
3
Output voltage
È
Idling output position
É
Mechanical stopper
Ê
Mechanical stopper
Ë
Effective electrical
Ì
angle
Sensor operating
Í
angle
30
20
10
0.68 V
10°
5°
95°
100°
110°
5°
1 - 12
GEN
FEATURES
Intake air pressure sensor and atmospheric pressure sensor
• Intake air pressure sensor
The intake air pressure sensor is used for measuring the intake air volume. The intake air volume of
every intake stroke is proportionate to the intake air pressure. Therefore, the intake air volume can be
measured by measuring the intake air pressure. The intake air pressure sensor converts the measured intake air pressure into electrical signals and sends those signals to the ECU. When the intake
air pressure is introduced into the sensor unit, which contains a vacuum chamber on one side of the
silicon diaphragm, the silicon chip that is mounted on the silicon diaphragm converts the intake air
pressure into electrical signals. Then, an integrated circuit (IC) amplifies and adjusts the signals and
makes temperature compensations, in order to generate electrical signals that are proportionate to
the pressure.
• Atmospheric pressure sensor
The atmospheric pressure sensor is used for making compensations to the changes in the air
density caused by the changes in the atmospheric pressure (particularly at high altitudes). The
operating principle and function of the atmospheric pressure sensor are the same as those of the
aforementioned intake air pressure sensor.
INFO
EMI shield
1
Sensor unit
2
Through condenser
3
Hybrid IC
4
Cap
5
Silicon diaphragm
6
Vacuum chamber
7
Solder
8
Silicon chip
9
Gold wire
0
A
B
C
D
1 - 13
(V)
P
Lead pin
Stem
Pressure induction pipe
Atmospheric pressure,
intake air pressure
Output voltage
È
Input pressure
É
GEN
FEATURES
Coolant temperature sensor
The signals from the coolant temperature sensor are used primarily for making fuel volume compensations during starting and warm-up. The coolant temperature sensor converts the temperature of
the coolant into electrical signals and sends them to the ECU.
15.5
0.322
INFO
80
Ω
Connector
1
Terminal
2
Tube
3
Thermistor
4
-200204060
Holder
5
Resistance k
È
Temperature °C
É
Intake temperature sensor
The intake temperature sensor corrects the deviation of the air-fuel mixture that is associated with
the changes in the intake air density, which are created by the changes in the intake air temperature
that occur due to atmospheric temperatures. This sensor uses a semi-cond ucto r the rmistor that has
a large resistance at low temperatures and a small resistance at high temperatures. The thermistor
converts the temperature-dependent changes in resistance into electrical resistance values, which
are then input into the ECU.
6.0
Connector
1
Terminal
2
Tube
3
Thermistor
4
Holder
5
Resistance k
È
Temperature °C
É
0.34
-200204060
Ω
80
1 - 14
GEN
FEATURES
O2 sensor
2
The O
maintaining the air-fuel mixture near the stoichiometric ratio (14.7:1). This sensor, which is a zirconia type, utilizes the oxygen ion conductivity of the solid electrolyte for detecting the oxygen concentration levels. In actual operation, a zirconia tube made of solid electrolyte is exposed in the exhaust
gas, so that the exterior of the zirconia tube is in contact with the exhaust gas and the interior is in
contact with the atmosphere whose oxygen concentration level is known. When a difference in the
oxygen concentration level is created between the outside and the inside of the zirconia tube, the
oxygen ion passes through the zirconia element and generates an electromotive force. The electromotive force increases when the oxygen concentration level is low (rich air-fuel ratio) and the electromotive force decreases when the oxygen concentration level is high (lean air-fuel ratio). As
electromotive force is generated in accordance with the concentration of the exhaust gas, the resultant voltage is input into the ECU in order to correct the duration of the injection of fuel.
sensor has been adopted to enable the catalyst to function at a high degree of efficiency by
INFO
Inner cover
1
Outer cover
2
Zirconia tube
3
Exhaust gas
4
Atmosphere
5
È
É
Ê
1 - 15
Atmosphere
Inner electrode
Zirconia element
Outer electrode
Ë
Porous ceramic layer
Ì
Exhaust gas
Í
GEN
FEATURES
Lean angle cut-off switch
The lean angle cut-off switch stops the supply of fuel to the engine in case the motorcycle overturns.
When the motorcycle is in the normal state, the cut-off switch outputs a constant voltage of approximately 1.0 V (low level). When the motorcycle tilts, the float in the switch tilts in proportion to the tilt
of the motorcycle. However, the voltage output to the ECU remains unchanged at the low level.
When the tilt of the motorcycle exceeds 70 degrees (according to the tilt of the float), the signal from
the sensor increases to approximately 4.0 V (high level). When the ECU receives the high-level voltage, it determines that the motorcycle has overturned, and stops the delivery of fuel to the engine by
turning OFF the fuel injection system relay that powers the fuel pump and the injectors. Once the
cut-off switch is tripped, the ECU maintains this state; therefore, even if the motorcycle has recovered its upright position, this state will not be canceled unless the main switch is turned OFF, and
then turned back ON.
INFO
Thyristor
1
IC unit
2
O-ring
3
Shaft
4
Float
5
V
4.0
1.0
20° 40° 60° 80°
Output voltage
È
High level
É
Low level
Ê
Cut-off switch tilt angle
Ë
Fuel injection system
Ì
relay OFF
70°
70°
70°
1 - 16
GEN
FEATURES
FUEL INJECTION SYSTEM
Operation and control
The fuel injection timing, injection duration, ignition timing, and the coil energizing duration are controlled by the ECU. To determine the basic injection timing, the ECU calculates the intake air volume
through the signals from the intake air pressure sensor, throttle position sensor, cylinder identification sensor, and crankshaft position sensor.
Furthermore, the ECU calculates the final injection timing by adding the following compensations to
the aforementioned basic injection duration: those obtained from the state of acceleration, as well
as those based on the signals from various sensors such as the coolant temperature, intake temperature, atmospheric, and exhaust pipe oxygen concentration level. At the same time, the ECU
assesses the crankshaft position through the signals from the cylinder identification sensor and the
crankshaft position sensor. Then, when the ECU determines that it is time to inject fuel, it sends an
injection command to the injectors. Furthermore, the ECU also controls the length of time the coil is
energized by calculating the ignition timing and the coil energizing duration based on the signals
from these sensors.
Determining the basic injection duration
The intake air volume determines the basic injection duration. In order to operate the engine in an
optimal condition, it is necessary to supply fuel at an air-fuel ratio that corresponds appropriately to
the volume of intake air that is constantly changing, and to ignite it an appropriate timing. The ECU
controls the basic injection duration based on the intake air volume and engine speed data.
INFO
Detection of intake air volume
The intake air volume is detected primarily through the signals from the throttle position sensor and
the intake air pressure sensor. The intake air volume is determined in accordance with the signals
from the atmospheric pressure sensor, intake temperature sensor, and the engine speed data.
Composition of basic injection duration
RPM
È
Injection duration
É
Cranking
Ê
Warm-up
Ë
Idle
Ì
Acceleration
Í
Î
Ï
Ð
1 - 17
Constant
Deceleration
Start
After start
Ñ
Basic injection dura-
Ò
tion
Voltage compensation
Ó
duration
GEN
FEATURES
Determining the final injection duration
The intake air volume determines the basic injection duration. However, at a given intake air volume, the volume of fuel that is required varies by the engine operating conditions such as acceleration or deceleration, or by weather conditions. This system uses various sensors to precisely check
these conditions, applies compensations to the basic injection duration, and determines the final
injection duration based on the operating condition of the engine.
INFO
Intake air pressure
Engine rpm
Degree of
opening of
throttle
Basic injection
quantity
Atmospheric
pressure
Water
temperature
Compensation
Battery voltage
Injection
command
Intake air
temperature
The fuel is cut off under conditions that do not require fuel, in order to stop the injection.
Reactive injection duration:
A lag is created between the time the ECU outputs a fuel injection signal to the injector and the time
the injector actually opens. Therefore, the ECU calculates this lag in advance before sending the
actuation signal to the injector. The battery voltage determines the reactive injection duration.
• High voltage → short reactive injection duration
• Low voltage → long reactive injection duration
LIST OF FUEL INJECTION COMPENSATIONS
Compensation itemCheck itemSensor used
Starti ng injection *1Coolant temperatureCoolant temperature sensor
After-start injection:
After-start enrichment *2Coolant temperatureCoolant temperature sensor
Warm-up enrichment *3Coolant temperatureCoolant temperature sensor
Intake temperature compensation *4Intake temperatureIntake temperature sensor
Acceleration compensation/decelera-
Intake air pressureIntake air pressure sensor
tion compensation *5
Throttle positionThrottle position sensor
Coolant temperatureCoolant temperature sensor
Air-fuel ratio feedback compensation*6Exhaust gas residual oxy-
gen concentration
1 - 19
2
O
sensor
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