2007 INFINITI QX56 fuel

ENGINE CONTROL SYSTEM
EC-27
< SERVICE INFORMATION >
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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 speed.
Electronic Ignition (EI) SystemINFOID:0000000003531587
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 signal. Comput-
ing 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
• 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)INFOID:0000000003531588
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
controlPower 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
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor
Vehicle speed*1
Sensor Input signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut control 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-28
< SERVICE INFORMATION >
ENGINE CONTROL SYSTEM
SYSTEM DESCRIPTION
If the engine speed is above 1,800 rpm under no load (for example, the shift position is neutral and engine
speed over is 1,800 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies
based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under EC-24, "
Multiport Fuel Injection (MFI) System".

EVAPORATIVE EMISSION SYSTEM
EC-33
< SERVICE INFORMATION >
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EVAPORATIVE EMISSION SYSTEM
DescriptionINFOID:0000000003531594
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 and
idling.
PBIB1631E

EC-36
< SERVICE INFORMATION >
EVAPORATIVE EMISSION SYSTEM
Check EVAP canister as follows:
1. Block port B.
2. Blow air into port Aand check that it flows freely out of port C.
3. Release blocked port B.
4. Apply vacuum pressure to port B and check that vacuum pres-
sure exists at the ports Aand C.
5. Block port Aand B.
6. Apply pressure to port C and check that there is no leakage.
FUEL TANK VACUUM RELIEF VALVE (BUILT INTO FUEL FILLER CAP)
1. Wipe clean valve housing.
2. Check valve opening pressure and vacuum.
3. If out of specification, replace fuel filler cap as an assembly.
CAUTION:
Use only a genuine fuel filler cap as a replacement. If an incor-
rect fuel filler cap is used, the MIL may come on.
EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Refer to EC-366and EC-373.
FUEL TANK TEMPERATURE SENSOR
Refer to EC-310and EC-314.
EVAP CANISTER VENT CONTROL VALVE
Refer to EC-379and EC-386.
EVAP CONTROL SYSTEM PRESSURE SENSOR
Refer to EC-392, EC-395and EC-401.
EVAP SERVICE PORT
PBIB1212E
SEF445Y
Pressure:
15.3 - 20.0 kPa (0.156 - 0.204 kg/cm2, 2.22 -
2.90 psi)
Vacuum:
−6.0 to −3.3 kPa (−0.061 to −0.034 kg/cm
2,
−0.87 to −0.48 psi)
SEF943S

EVAPORATIVE EMISSION SYSTEM
EC-37
< SERVICE INFORMATION >
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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 InstallationINFOID:0000000003531596
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 LeakageINFOID:0000000003531597
CAUTION:
• Never use compressed air or a high pressure pump.
• Do not exceed 4.12 kPa (0.042 kg/cm
2, 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.
BBIA0366E
: N-·m (kg-m, in-lb)
BBIA0349E
BBIA0350E

EC-40
< SERVICE INFORMATION >
ON BOARD REFUELING VAPOR RECOVERY (ORVR)
ON BOARD REFUELING VAPOR RECOVERY (ORVR)
System DescriptionINFOID:0000000003531598
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 CO
2 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-80, "
Fuel Pressure Check" .
- 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.
Diagnosis ProcedureINFOID:0000000003531599
SYMPTOM: FUEL ODOR FROM EVAP CANISTER IS STRONG.
1.CHECK EVAP CANISTER
1. Remove EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
2. Weigh the EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
The weight should be less than 2.5 kg (5.5 lb).
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2.CHECK IF EVAP CANISTER SATURATED WITH WATER
PBIB1068E

ON BOARD REFUELING VAPOR RECOVERY (ORVR)
EC-41
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Does water drain from the EVAP canister?
Ye s o r N o
Yes >> GO TO 3.
No >> GO TO 5.
3.REPLACE EVAP CANISTER
Replace EVAP canister with a new one.
>> GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the EVAP hose between EVAP canister and vehicle frame for clogging or poor connection.
>> Repair or replace EVAP hose.
5.CHECK REFUELING EVAP VAPOR CUT VALVE
Refer to EC-42, "
Component Inspection" .
OK or NG
OK >>INSPECTION END
NG >> Replace refueling EVAP vapor cut valve with fuel tank.
SYMPTOM: CANNOT REFUEL/FUEL ODOR FROM THE FUEL FILLER OPENING IS STRONG
WHILE REFUELING.
1.CHECK EVAP CANISTER
1. Remove EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
2. Weigh the EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
The weight should be less than 2.5 kg (5.5 lb).
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2.CHECK IF EVAP CANISTER SATURATED WITH WATER
Does water drain from the EVAP canister?
Ye s o r N o
Yes >> GO TO 3.
No >> GO TO 5.
3.REPLACE EVAP CANISTER
Replace EVAP canister with a new one.
>> GO TO 4.
BBIA0351E
BBIA0351E

EC-42
< SERVICE INFORMATION >
ON BOARD REFUELING VAPOR RECOVERY (ORVR)
4.DETECT MALFUNCTIONING PART
Check the EVAP hose between EVAP canister and vehicle frame for clogging or poor connection.
>> Repair or replace EVAP hose.
5.CHECK VENT HOSES AND VENT TUBES
Check hoses and tubes between EVAP canister and refueling EVAP vapor cut valve for clogging, kink, loose-
ness and improper connection.
OK or NG
OK >> GO TO 6.
NG >> Repair or replace hoses and tubes.
6.CHECK FILLER NECK TUBE
Check recirculation line for clogging, dents and cracks.
OK or NG
OK >> GO TO 7.
NG >> Replace filler neck tube.
7.CHECK REFUELING EVAP VAPOR CUT VALVE
Refer to EC-42, "
Component Inspection" .
OK or NG
OK >> GO TO 8.
NG >> Replace refueling EVAP vapor cut valve with fuel tank.
8.CHECK FUEL FILLER TUBE
Check filler neck tube and hose connected to the fuel tank for clogging, dents and cracks.
OK or NG
OK >> GO TO 9.
NG >> Replace fuel filler tube.
9.CHECK ONE-WAY FUEL VALVE-I
Check one-way valve for clogging.
OK or NG
OK >> GO TO 10.
NG >> Repair or replace one-way fuel valve with fuel tank.
10.CHECK ONE-WAY FUEL VALVE-II
1. Make sure that fuel is drained from the tank.
2. Remove fuel filler tube and hose.
3. Check one-way fuel valve for operation as follows.
When a stick is inserted, the valve should open, when removing
stick it should close.
Do not drop any material into the tank.
OK or NG
OK >>INSPECTION END
NG >> Replace fuel filler tube or replace one-way fuel valve
with fuel tank.
Component InspectionINFOID:0000000003531600
REFUELING EVAP VAPOR CUT VALVE
With CONSULT-II
1. Remove fuel tank. Refer to FL-10.
SEF665U