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Nissan Quest E52. Manual - part 457

EC-38

< SYSTEM DESCRIPTION >

[VQ35DE]

SYSTEM

DTC No.

Detected items

Engine operating condition in fail-safe mode

P0011

P0021

Intake valve timing control

The signal is not energized to the intake valve timing control solenoid valve and the valve
control does not function.

P0101
P0102
P0103

Mass air flow sensor circuit

Engine speed will not rise more than 2,400 rpm due to the fuel cut.

P0117
P0118

Engine coolant tempera-
ture sensor circuit

Engine coolant temperature will be determined by ECM based on the following condition.
CONSULT displays the engine coolant temperature decided by ECM.

Condition

Engine coolant temperature decided

(CONSULT display)

Just as ignition switch is turned ON
or START

C (104

Approx 4 minutes or more after en-
gine starting

C (176

Except as shown above

40 - 80

C (104 - 176

(Depends on the time)

When the fail-safe system for engine coolant temperature sensor is activated, the cooling
fan operates while engine is running.

P0122
P0123
P0222
P0223
P2135

Throttle position sensor

The ECM controls the electric throttle control actuator in regulating the throttle opening in
order for the idle position to be within +10 degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal
condition.
Therefore, the acceleration will be poor.

P0196
P0197
P0198

Engine oil temperature
sensor

Intake valve timing control does not function.

P0500

Vehicle speed sensor

The cooling fan operates (Highest) while engine is running.

P0605

ECM

(When ECM calculation function is malfunctioning:)
ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.
ECM deactivates ASCD operation.

P0643

Sensor power supply

ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.

P1805

Brake switch

ECM controls the electric throttle control actuator by regulating the throttle opening to a
small range.
Therefore, acceleration will be poor.

Vehicle condition

Driving condition

When engine is idling

Normal

When accelerating

Poor acceleration

P2100
P2103

Throttle control motor relay

ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.

P2101

Electric throttle control
function

ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.

P2118

Throttle control motor

ECM stops the electric throttle control actuator control, throttle valve is maintained at a
fixed opening (approx. 5 degrees) by the return spring.

SYSTEM

EC-39

< SYSTEM DESCRIPTION >

[VQ35DE]

MULTIPORT FUEL INJECTION SYSTEM

MULTIPORT FUEL INJECTION SYSTEM : System Description

INFOID:0000000009650957

SYSTEM DIAGRAM

INPUT/OUTPUT SIGNAL CHART

P2119

Electric throttle control ac-
tuator

(When electric throttle control actuator does not function properly due to the return spring
malfunction:)
ECM controls the electric throttle actuator by regulating the throttle opening around the
idle position. The engine speed will not rise more than 2,000 rpm.

(When throttle valve opening angle in fail-safe mode is not in specified range:)
ECM controls the electric throttle control actuator by regulating the throttle opening to 20
degrees or less.

(When ECM detects the throttle valve is stuck open:)
While the vehicle is being driven, it slows down gradually because of fuel cut. After the
vehicle stops, the engine stalls.
The engine can restart in the N or P position, and engine speed will not exceed 1,000 rpm
or more.

P2122
P2123
P2127
P2128
P2138

Accelerator pedal position
sensor

DTC No.

Detected items

Engine operating condition in fail-safe mode

JMBIA1833GB

EC-40

< SYSTEM DESCRIPTION >

[VQ35DE]

SYSTEM

*1: This sensor is not used to control the engine system under normal conditions.

*2: This signal is sent to the ECM via the 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 position is changed from N to D
• High-load, high-speed operation

• During deceleration
• During high engine speed operation

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)

Sensor

Input signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)

Engine speed*

Piston position

Fuel injection
& mixture ratio
control

Fuel 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

Gear position

Battery

Battery voltage*

Knock sensor

Engine knocking condition

Power steering pressure sensor

Power steering operation

Heated oxygen sensor 2*

Density of oxygen in exhaust gas

ABS actuator and electric unit (control unit)

VDC/TCS operation command*

Combination meter

Vehicle speed*

BCM

Air conditioner operation*

PBIB3020E

SYSTEM

EC-41

< SYSTEM DESCRIPTION >

[VQ35DE]

The mixture ratio feedback system provides the best air-fuel mixture ratio for drive ability 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-27, "Air Fuel Ratio (A/F) Sensor 1"

. This maintains the mixture ratio within the range of stoichiometric

(ideal air-fuel mixture).
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.

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 ignition 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.

SEF179U

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