Infiniti FX35, FX50 (S51). Manual - part 624

ENGINE CONTROL SYSTEM

EC-37

< SYSTEM DESCRIPTION >

[VQ35HR]

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Component Description

INFOID:0000000005236697

1.

ICC steering switch

2.

CANCEL switch

3.

RESUME/ACCELERATE switch

4.

SET/COAST switch

5.

DISTANCE switch

6.

MAIN switch

7.

LDP/DCA switch

1.

ASCD steering switch

2.

CANCEL switch

3.

RESUME/ACCELERATE switch

4.

SET/COAST switch

5.

MAIN switch

1.

Snow mode switch

JSBIA0155ZZ

JSBIA0156ZZ

JMBIA1623ZZ

Component

Reference

A/F sensor 1

EC-200, "Description"

A/F sensor 1 heater

EC-156, "Description"

Accelerator pedal position sensor

EC-442, "Description"

ASCD brake switch

EC-422, "Description"

ASCD steering switch

EC-415, "Description"

Battery current sensor

EC-397, "Description"

Camshaft position sensor

EC-273, "Description"

Crankshaft position sensor

EC-268, "Description"

EC-38

< SYSTEM DESCRIPTION >

[VQ35HR]

ENGINE CONTROL SYSTEM

Cooling fan control module

EC-464, "Description"

Cooling fan motor

EC-464, "Description"

Electric throttle control actuator

EC-388, "Description"

Engine coolant temperature sensor

EC-186, "Description"

Engine oil temperature sensor

EC-249, "Description"

EVAP canister purge volume control solenoid valve

EC-295, "Description"

EVAP canister vent control valve

EC-303, "Description"

EVAP control system pressure sensor

EC-311, "Description"

Exhaust valve timing control magnet retarder

EC-165, "Description"

Exhaust valve timing control position sensor

EC-365, "Description"

Fuel injector

EC-470, "Description"

Fuel level sensor

EC-339, "Description"

Fuel pump

EC-473, "Description"

Fuel tank temperature sensor

EC-243, "Description"

Heated oxygen sensor 2

EC-215, "Description"

Heated oxygen sensor 2 heater

EC-159, "Description"

ICC brake switch

EC-428, "Description"

ICC steering switch

EC-418, "Description"

Ignition coil with power transistor

EC-480, "Description"

Intake air temperature sensor

EC-181, "Description"

Intake valve timing control solenoid valve

EC-162, "Description"

Knock sensor

EC-265, "Description"

Mass air flow sensor

EC-168, "Description"

PCV valve

EC-492, "Description"

Power steering pressure sensor

EC-351, "Description"

Refrigerant pressure sensor

EC-494, "Description"

Snow mode switch

EC-496, "Description"

Stop lamp switch

EC-439, "Description"

Throttle control motor

EC-385, "Description"

Throttle control motor relay

EC-393, "Description"

Throttle position sensor

EC-189, "Description"

Component

Reference

MULTIPORT FUEL INJECTION SYSTEM

EC-39

< SYSTEM DESCRIPTION >

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MULTIPORT FUEL INJECTION SYSTEM

System Diagram

INFOID:0000000005236698

System Description

INFOID:0000000005236699

INPUT/OUTPUT SIGNAL CHART

*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.

JMBIA1534GB

Sensor

Input Signal to ECM

ECM function

Actuator

Crankshaft position sensor

Engine speed*

3 

& Piston position

Fuel injection 
& mixture ratio 
control

Fuel injector

Camshaft position sensor

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*

3

Knock sensor

Engine knocking condition

Power steering pressure sensor

Power steering operation

Heated oxygen sensor 2*

1

Density of oxygen in exhaust gas

ABS actuator and electric unit (control unit)

VDC/TCS operation command*

2

Unified meter and A/C amp.

Vehicle speed & Air conditioner opera-

tion*

2

EC-40

< SYSTEM DESCRIPTION >

[VQ35HR]

MULTIPORT FUEL INJECTION SYSTEM

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, camshaft position sen-
sor 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.

<Fuel increase>

• 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

<Fuel decrease>

• During deceleration
• During high engine speed operation

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 1 can better reduce CO, HC and NOx emissions. This system uses A/F sensor 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-200,

"Description"

. 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 1. Even if the switching characteris-
tics of A/F sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal from heated oxygen sen-
sor 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.

PBIB3020E