2008 NISSAN TEANA engine

EC-26
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
ENGINE CONTROL SYSTEM
Throttle control motor relayEC-294, "Description"
Throttle position sensorEC-160, "Description"
VIAS control solenoid valve 1EC-285, "Description"
VIAS control solenoid valve 2EC-288, "Description"
Component Reference

EC-28
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
MULTIPORT FUEL INJECTION SYSTEM
*1: This sensor is not used to control the engine system under normal conditions.
*2: This signal is sent to the ECM through CAN communication line.
*3: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from the crankshaft position sensor (POS), camshaft position
sensor (PHASE) and the mass air flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated to improve engine performance under various operat-
ing conditions as listed below.

 During warm-up
 When starting the engine
 During acceleration
 Hot-engine operation
 When selector lever is changed from N to D
 High-load, high-speed operation
 During deceleration
 During high engine speed operation
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Intake air temperature sensor Intake air temperature
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
TCM (VQ35DE engine)
Park/neutral position (PNP) switch (VQ25DE engine)Gear position
Battery
Battery voltage*
3
Knock sensor Engine knocking condition
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit)
VDC/TCS operation command*
2
BCM
Air conditioner operation*2
ABS actuator and electric unit (control unit)
Vehicle speed*2

MULTIPORT FUEL INJECTION SYSTEM
EC-29
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
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MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can better reduce CO, HC and NOx emissions. This system uses A/F sen-
sor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The ECM adjusts the
injection pulse width according to the sensor voltage signal. For more information about A/F sensor 1, refer to
EC-163, "
Description". This maintains the mixture ratio within the range of stoichiometric (ideal air-fuel mix-
ture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching
characteristics of A/F sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal from heated
oxygen sensor 2.
 Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.
- Deceleration and acceleration
- High-load, high-speed operation
- Malfunction of A/F sensor 1 or its circuit
- Insufficient activation of A/F sensor 1 at low engine coolant temperature
- High engine coolant temperature
- During warm-up
- After shifting from N to D
- When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short-term fuel trim and long-term fuel trim.
“Short-term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in
fuel volume if it is lean.
“Long-term fuel trim” is overall fuel compensation carried out over time to compensate for continual deviation
of the short-term fuel trim from the central value. Continual deviation will occur due to individual engine differ-
ences, wear over time and changes in the usage environment.
PBIB3020E

EC-30
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
MULTIPORT FUEL INJECTION SYSTEM
FUEL INJECTION TIMING
Two types of systems are used.
 Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
 Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all six cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The six injectors will then receive the signals 2 times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speeds.
SEF179U

MULTIPORT FUEL INJECTION SYSTEM
EC-31
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
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Component Parts LocationINFOID:0000000003857771
1. Intake valve timing control solenoid
valve (bank 1)2. Intake valve timing control solenoid
valve (bank 2)3. Electronic controlled engine mount
control solenoid valve
4. Fuel injector (bank 2) 5. Cooling fan motor-2 6. A/F sensor 1 (bank 2)
7. Ignition coil (with power transistor)
and spark plug (bank 2)8. Camshaft position sensor (PHASE)
(bank 2)9. Crankshaft position sensor (POS)
10. Engine coolant temperature sensor 11. Cooling fan motor-1 12. ECM
13. Refrigerant pressure sensor 14. Battery current sensor 15. IPDM E/R
16. Mass air flow sensor (with intake air
temperature sensor)17. Electric throttle control actuator 18. Power valve actuator 2 (VQ35DE
models)
19. EVAP canister purge volume control
solenoid valve20. Camshaft position sensor (PHASE)
(bank 1)21. Ignition coil (with power transistor)
and spark plug (bank 1)
22. A/F sensor 1 (bank 1) 23. Fuel injector (bank 1) 24. VIAS control solenoid valve 1 and 2
(VQ35DE models)
25. Power valve actuator 1
JMBIA1373ZZ

EC-34
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
MULTIPORT FUEL INJECTION SYSTEM
1. A/F sensor 1 (bank 1) harness con-
nector2. A/F sensor 1 (bank 1) 3. A/F sensor 1 (bank 2) harness con-
nector
4. A/F sensor 1 (bank 2)
: Vehicle front
1. HO2S2 (bank 1) 2. HO2S2 (bank 2) 3. HO2S2 (bank 2) harness connector
4. Tie-rod (RH) 5. Power steering pressure sensor 6. HO2S2 (bank 1) harness connector
: Vehicle front
1. Electronic controlled engine mount
control solenoid valve2. VIAS control solenoid valve 1 3. VIAS control solenoid valve 2
4. EVAP canister purge volume control
solenoid valve
JMBIA1116ZZ
JMBIA1380ZZ
JMBIA1381GB

MULTIPORT FUEL INJECTION SYSTEM
EC-35
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
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1. Electronic controlled engine mount
control solenoid valve2. VIAS control solenoid valve 3. EVAP canister purge volume control
solenoid valve
1. Intake valve timing control solenoid
valve (bank 1)2. Intake valve timing control solenoid
valve (bank 2)3. Data link connector
1. Stop lamp switch 2. ASCD brake switch 3. Accelerator pedal position sensor
1. ASCD steering switch 2. CANCEL switch 3. RESUME/ACCELERATE switch
4. SET/COAST switch 5. MAIN switch
JMBIA1382GB
JMBIA1383ZZ
JMBIA1384ZZ
JMBIA1120ZZ

EC-36
< FUNCTION DIAGNOSIS >[VQ25DE, VQ35DE]
MULTIPORT FUEL INJECTION SYSTEM
Component Description
INFOID:0000000003856468
1. Fuel level sensor unit and fuel pump
harness connector2. Fuel pressure regulator 3. Fuel level sensor unit and fuel pump
: Vehicle front
JMBIA1385ZZ
Component Reference
A/F sensor 1EC-163, "
Description"
Accelerator pedal position sensorEC-304, "Description"
Camshaft position sensor (PHASE)EC-222, "Description"
Crankshaft position sensor (POS)EC-218, "Description"
Engine coolant temperature sensorEC-157, "Description"
Fuel injectorEC-334, "Description"
Heated oxygen sensor 2EC-178, "Description"
Intake air temperature sensorEC-154, "Description"
Knock sensorEC-215, "Description"
Mass air flow sensorEC-149, "Description"
Park/neutral position switchEC-245, "Description"
Power steering pressure sensorEC-236, "Description"
Throttle position sensorEC-160, "Description"