engine INFINITI FX35 2007 Service Manual

EC-692
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
Multiport Fuel Injection (MFI) SystemNBS004JO
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 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
control Fuel injector
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
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
Park/neutral position (PNP) switch 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
Air conditioner switch Air conditioner operation
Wheel sensor Vehicle speed*
2

ENGINE CONTROL SYSTEM EC-693
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Revision: 2006 July 2007 FX35/FX45
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 then 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-901
. 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 long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
PBIB3020E

EC-694
[VK45DE]
ENGINE CONTROL SYSTEM
Revision: 2006 July 2007 FX35/FX45
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 eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight fuel injectors will then receive the signals two 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.
Electronic Ignition (EI) SystemNBS004JP
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Firing order: 1 - 8 - 7 - 3 - 6 - 5 - 4 - 2
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor (PHASE) sig-
nal. Computing this information, ignition signals are transmitted to the power transistor.
During the following conditions, the ignition timing is revised by the ECM according to the other data stored in
the ECM.

At starting

During warm-up

At idle

At low battery voltage
PBIB0122E
Sensor Input Signal to ECM ECM function Actuator
Crankshaft position sensor (POS) Engine speed*
2
Piston position
Ignition timing
control Power transistor
Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Battery Battery voltage*
2
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Wheel sensor Vehicle speed*
1

ENGINE CONTROL SYSTEM EC-695
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Revision: 2006 July 2007 FX35/FX45

During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.
Fuel Cut Control (at No Load and High Engine Speed)NBS004JQ
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
If the engine speed is above 1,400 rpm under no load (for example, the selector lever position is neutral and
engine speed is over 1,400 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off var-
ies based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,000 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under Multiport Fuel Injection (MFI) System, EC-692
.
Sensor Input Signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut con-
trol Fuel injector
Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE) Engine speed
Wheel sensor Vehicle speed*

EC-696
[VK45DE]
AIR CONDITIONING CUT CONTROL
Revision: 2006 July 2007 FX35/FX45
AIR CONDITIONING CUT CONTROLPFP:23710
Input/Output Signal ChartNBS00415
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
System DescriptionNBS00416
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.

When the accelerator pedal is fully depressed.

When cranking the engine.

At high engine speeds.

When the engine coolant temperature becomes excessively high.

When operating power steering during low engine speed or low vehicle speed.

When engine speed is excessively low.

When refrigerant pressure is excessively low or high.
Sensor Input Signal to ECM ECM function Actuator
Air conditioner switch Air conditioner ON signal*
1
Air conditioner
cut control Air conditioner relay
Accelerator pedal position sensor Accelerator pedal position
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE) Engine speed*
2
Engine coolant temperature sensor Engine coolant temperature
Battery Battery voltage*
2
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
Wheel sensor Vehicle speed*
1

AUTOMATIC SPEED CONTROL DEVICE (ASCD) EC-697
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Revision: 2006 July 2007 FX35/FX45
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionNBS00417
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line
BASIC ASCD SYSTEM
Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can set vehicle speed in advance between approximately 40 km/
h (25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric throttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE lamp and SET lamp in combination meter. If any malfunc-
tion occurs in ASCD system, it automatically deactivates control.
NOTE:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.
SET OPERATION
Press MAIN switch. (The CRUISE lamp in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press SET/COAST switch. (Then SET lamp in combination meter illuminates.)
ACCELERATE OPERATION
If the RESUME/ACCELERATE switch is pressed during cruise control driving, increase the vehicle speed until
the switch is released or vehicle speed reaches maximum speed controlled by the system.
And then ASCD will keep the new set speed.
CANCEL OPERATION
When any of following conditions exist, cruise operation will be canceled.

CANCEL switch is pressed

More than 2 switches at ASCD steering switch are pressed at the same time (Set speed will be cleared)

Brake pedal is depressed

Selector lever is changed to N, P, R position

Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed

TCS system is operated
When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.

Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE lamp will
stop blinking and the cruise operation will be able to work by pressing SET/COAST switch or RESUME/
ACCELERATE switch.

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
COAST OPERATION
When the SET/COAST switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.
Sensor Input signal to ECM ECM function Actuator
ASCD brake switch Brake pedal operation
ASCD vehicle speed control Electric throttle control
actuator
Stop lamp switch Brake pedal operation
ASCD steering switch ASCD steering switch operation
Park/neutral position (PNP) switch Gear position
Wheel sensor Vehicle speed*
TCM Powertrain revolution*

EC-700
[VK45DE]
EVAPORATIVE EMISSION SYSTEM
Revision: 2006 July 2007 FX35/FX45
EVAPORATIVE EMISSION SYSTEMPFP:14950
DescriptionNBS0041A
SYSTEM DESCRIPTION
The evaporative emission system is used to reduce hydrocarbons emitted into the atmosphere from the fuel
system. This reduction of hydrocarbons is accomplished by activated charcoals in the EVAP canister.
The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the
vapor is stored there when the engine is not operating or when refueling to the fuel tank.
The vapor in the EVAP canister is purged by the air through the purge line to the intake manifold when the
engine is operating. EVAP canister purge volume control solenoid valve is controlled by ECM. When the
engine operates, the flow rate of vapor controlled by EVAP canister purge volume control solenoid valve is
proportionally regulated as the air flow increases.
EVAP canister purge volume control solenoid valve also shuts off the vapor purge line during decelerating.
PBIB1631E

EC-704
[VK45DE]
EVAPORATIVE EMISSION SYSTEM
Revision: 2006 July 2007 FX35/FX45
EVAP SERVICE PORT
Positive pressure is delivered to the EVAP system through the EVAP
service port. If fuel vapor leakage in the EVAP system occurs, use a
leak detector to locate the leak.
Removal and InstallationNBS0041C
EVAP CANISTER
Tighten EVAP canister as shown in the figure.
EVAP CANISTER VENT CONTROL VALVE
1. Turn EVAP canister vent control valve counterclockwise.
2. Remove the EVAP canister vent control valve.
Always replace O-ring with a new one.
How to Detect Fuel Vapor LeakageNBS0041D
CAUTION:

Do not use compressed air or a high pressure pump.

Do not exceed 4.12 kPa (0.042 kg/cm2 , 0.6 psi) of pressure in EVAP system.
NOTE:

Do not start engine.

Improper installation of EVAP service port adapter to the EVAP service port may cause a leak.
SEF462UA
PBIB1628E
PBIB1030E

ON BOARD REFUELING VAPOR RECOVERY (ORVR) EC-707
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ON BOARD REFUELING VAPOR RECOVERY (ORVR)PFP:00032
System DescriptionNBS0041E
From the beginning of refueling, the air and vapor inside the fuel tank go through refueling EVAP vapor cut
valve and EVAP/ORVR line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is
released to the atmosphere.
When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and
refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged
during driving.
WARNING:
When conducting inspections below, be sure to observe the following:

Put a “CAUTION: FLAMMABLE” sign in workshop.

Do not smoke while servicing fuel system. Keep open flames and sparks away from work area.

Be sure to furnish the workshop with a CO2 fire extinguisher.
CAUTION:

Before removing fuel line parts, carry out the following procedures:
–Put drained fuel in an explosion-proof container and put lid on securely.
–Release fuel pressure from fuel line. Refer to EC-747, "FUEL PRESSURE RELEASE" .
–Disconnect battery ground cable.

Always replace O-ring when the fuel gauge retainer is removed.

Do not kink or twist hose and tube when they are installed.

Do not tighten hose and clamps excessively to avoid damaging hoses.

After installation, run engine and check for fuel leaks at connection.

Do not attempt to top off the fuel tank after the fuel pump nozzle shuts off automatically.
Continued refueling may cause fuel overflow, resulting in fuel spray and possibly a fire.
PBIB1068E

EC-712
[VK45DE]
POSITIVE CRANKCASE VENTILATION
Revision: 2006 July 2007 FX35/FX45
POSITIVE CRANKCASE VENTILATIONPFP:11810
DescriptionNBS0041H
SYSTEM DESCRIPTION
This system returns blow-by gas to the intake manifold.
The positive crankcase ventilation (PCV) valve is provided to conduct crankcase blow-by gas to the intake
manifold.
During partial throttle operation of the engine, the intake manifold sucks the blow-by gas through the PCV
valve.
Normally, the capacity of the valve is sufficient to handle any blow-by and a small amount of ventilating air.
The ventilating air is then drawn from the air inlet tubes into the crankcase. In this process the air passes
through the hose connecting air inlet tubes to rocker cover.
Under full-throttle condition, the manifold vacuum is insufficient to draw the blow-by flow through the valve.
The flow goes through the hose connection in the reverse direction.
On vehicles with an excessively high blow-by, the valve does not
meet the requirement. This is because some of the flow will go
through the hose connection to the air inlet tubes under all condi-
tions.
Component InspectionNBS0041I
PCV (POSITIVE CRANKCASE VENTILATION) VALVE
With engine running at idle, remove PCV valve from rocker cover. A
properly working valve makes a hissing noise as air passes through
it. A strong vacuum should be felt immediately when a finger is
placed over valve inlet.
PBIB0062E
PBIB1588E
PBIB1589E