2008 INFINITI QX56 Fuel

EC-484
< SYMPTOM DIAGNOSIS >[VK56DE]
ENGINE CONTROL SYSTEM SYMPTOMS
1 - 6: The numbers refer to the order of inspection.Exhaust Exhaust manifold/Tube/Muffler/
Gasket 55555 55 5EM-30
,
EX-
5Three way catalyst
Lubrica-
tion Oil pan/Oil strainer/Oil pump/Oil
filter/Oil gallery/Oil cooler
55555 55 5EM-33
,
LU-
14 , LU-11 ,
LU-12
Oil level (Low)/Filthy oil LU-8, "In-
spection"
Cooling Radiator/Hose/Radiator filler cap
55555 55 45 CO-15
Thermostat
5CO-22
Water pump CO-20
Water galleryCO-6
Cooling fan5CO-18,
CO-
19
Coolant level (Low)/Contaminat-
ed coolant 5
CO-10
IVIS (INFINITI Vehicle Immobilizer System —
NATS) 11
SEC-8
SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Revision: March 2010 2008 QX56

NORMAL OPERATING CONDITIONEC-485
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NORMAL OPERATING CONDITION
Fuel Cut Control (at No
Load and High Engine Speed)INFOID:0000000001351235
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
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-28, "
System Description".
Sensor Input signal to ECMECM functionActuator
TCM 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*
Revision: March 2010 2008 QX56

PRECAUTIONSEC-487
< PRECAUTION > [VK56DE]
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5. When the repair work is completed, return the ignition switch to the
″LOCK ″ position before connecting
the battery cables. (At this time, the steering lock mechanism will engage.)
6. Perform a self-diagnosis check of al l control units using CONSULT-III.
On Board Diagnosis (OBD) System of Engine and A/TINFOID:0000000001351222
The ECM has an on board diagnostic system . It will light up the malfunction indicator lamp (MIL) to warn the
driver of a malfunction causing emission deterioration.
CAUTION:
• Be sure to turn the ignition switch OFF and di sconnect the negative battery cable before any repair
or inspection work. The open/short circuit of re lated switches, sensors, solenoid valves, etc. will
cause the MIL to light up.
• Be sure to connect and lock the connectors secure ly after work. A loose (unlocked) connector will
cause the MIL to light up due to the open circuit. (Be sure the connector is free from water, grease,
dirt, bent terminals, etc.)
• Certain systems and components, especially those related to OBD, may use a new style slide-lock-
ing type harness connector. For description and how to disconnect, refer to PG-65
.
• Be sure to route and secure the harnesses properly after work. The interference of the harness with
a bracket, etc. may cause the MIL to li ght up due to the short circuit.
• Be sure to connect rubber tubes properly afte r work. A misconnected or disconnected rubber tube
may cause the MIL to light up due to the malfuncti on of the EVAP system or fuel injection system,
etc.
• Be sure to erase the unnecessary malfunction information (repairs completed) from the ECM and TCM (Transmission control module) before returning the vehicle to the customer.
PrecautionINFOID:0000000006211821
•Always use a 12 volt battery as power source.
• Do not attempt to disconnect battery cables while engine is
running.
• Before connecting or disc onnecting the ECM harness con-
nector, turn ignition switch OFF and disconnect negative bat-
tery cable. Failure to do so may damage the ECM because
battery voltage is applied to ECM even if ignition switch is
turned OFF.
• Before removing parts, turn ig nition switch OFF and then dis-
connect negative battery cable.
• Do not disassemble ECM.
• If a battery cable is disconnected, the memory will return to
the ECM value.
The ECM will now start to sel f-control at its initial value.
Engine operation can vary slight ly when the terminal is dis-
connected. However, this is not an indication of a malfunc-
tion. Do not replace parts because of a slight variation.
• If the battery is disconnected, the following emission-related
diagnostic information will be lost within 24 hours.
- Diagnostic trouble codes
- 1st trip diagnostic trouble codes
- Freeze frame data
- 1st trip freeze frame data
- System readiness test (SRT) codes
- Test values
-
Presumed ethanol mixture ratio
SEF289H
PBIB1164E
Revision: March 2010 2008 QX56

PRECAUTIONSEC-489
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•
When measuring ECM signals with a circuit tester, never allow
the two tester probes to contact.
Accidental contact of probes will cause a short circuit and
damage the ECM power transistor.
• Do not use ECM ground termina ls when measuring input/out-
put voltage. Doing so may result in damage to the ECM's tran-
sistor. Use a ground other than ECM terminals, such as the
ground.
• B1 indicates the bank 1, B2 indicates the bank 2 as shown in
the figure.
• Do not operate fuel pump when there is no fuel in lines.
• Tighten fuel hose clamps to the specified torque.
SEF348N
PBIB1144E
BBIA0402E
Revision: March 2010 2008 QX56

PREPARATIONEC-491
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PREPARATION
PREPARATION
Special Service ToolINFOID:0000000001351224
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool name
Description
EG17650301
(J-33984-A)
Radiator cap tester
adapter Adapting radiator cap tester to radiator cap and ra-
diator filler neck
a: 28 (1.10) dia.
b: 31.4 (1.236) dia.
c: 41.3 (1.626) dia.
Unit: mm (in)
KV10117100
(J-36471-A)
Heated oxygen sensor
wrench Loosening or tightening heated oxygen sensors
with 22 mm (0.87 in) hexagon nut
KV10114400
(J-38365)
Heated oxygen sensor
wrench Loosening or tightening heated oxygen sensors
a: 22 mm (0.87 in)
(J-44626)
Air fuel ratio (A/F) sen-
sor wrench Loosening or tightening air fuel ratio (A/F) sensor 1
(J-44321)
Fuel pressure gauge
kit Checking fuel pressure
(J-44321-6)
Fuel pressure adapter Connecting fuel pressure gauge to quick connec-
tor type fuel lines.
S-NT564
S-NT379
S-NT636
LEM054
LEC642
LBIA0376E
Revision: March 2010
2008 QX56

EC-492
< PREPARATION >[VK56DE]
PREPARATION
Commercial Service Tool
INFOID:0000000001351225
(J-45488)
Quick connector re-
lease Remove fuel tube quick connectors in engine
room.
(J-23688)
Engine coolant refrac-
tometer Checking concentration of ethylene glycol in en-
gine coolant
Tool number
(Kent-Moore No.)
Tool name
Description
PBIC0198E
WBIA0539E
Tool name
(Kent-Moore No.)
Description
Leak detector
i.e.: (J-41416) Locating the EVAP leak
EVAP service port
adapter
i.e.: (J-41413-OBD) Applying positive pressure through EVAP service
port
Fuel filler cap adapter
i.e.: (MLR-8382) Checking fuel tank vacuum relief valve opening
pressure
Socket wrench Removing and installing engine coolant tempera-
ture sensor
S-NT703
S-NT704
S-NT815
S-NT705
Revision: March 2010 2008 QX56

EC-494
< ON-VEHICLE MAINTENANCE >[VK56DE]
FUEL PRESSURE
ON-VEHICLE MAINTENANCE
FUEL PRESSURE
Fuel Pressure CheckINFOID:0000000001351336
FUEL PRESSURE RELEASE
With CONSULT-IIl
1. Turn ignition switch ON.
2. Perform “FUEL PRESSURE RELEASE” in
“WORK SUPPORT” mode with CONSULT-IIl.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel pressure.
5. Turn ignition switch OFF.
Without CONSULT-IIl
1. Remove fuel pump fuse located in IPDM E/R.
2. Start engine.
3. After engine stalls, crank it two or three times to release all fuel pressure.
4. Turn ignition switch OFF.
5. Reinstall fuel pump fuse after servicing fuel system.
FUEL PRESSURE CHECK
CAUTION:
• Before disconnecting fuel line, release fuel pr essure from fuel line to eliminate danger.
• Be careful not to scratch or get the fuel hose connection area dirty wh en servicing, so that the quick
connector o-ring ma intains sealability.
• Use Fuel Pressure Gauge Kit J-44321 and Fuel Pr essure Adapter J-44321-6 to check fuel pressure.
• Do not perform fuel pressure check with electrical system operating (i.e. lights, rear defog, A/C, etc.).
Fuel pressure gauge may indicate false readings du e to varying engine loads and changes in mani-
fold vacuum.
NOTE:
Prepare pans or saucers under the disconnected fuel line because the fuel may spill out. The fuel pres-
sure cannot be completely released because JA60 models do not have fuel return system.
1. Release fuel pressure to zero. Refer to "FUEL PRESSURE RELEASE".
2. Remove engine cover.
3. Remove fuel hose using Quick Connector Release J-45488. Refer to EM-26
.
• Do not twist or kink fuel hose because it is plastic hose.
• Do not remove fuel hose from quick connector.
• Keep fuel hose connections clean.
4. Install Fuel Pressure Adapter J-44321-6 and Fuel Pressure Gauge (from kit J-44321) as shown in figure.
• Do not distort or bend fuel rail tube when installing fuel pres-sure gauge adapter.
• When reconnecting fuel hose, check the original fuel hose for damage and abnormality.
5. Turn ignition switch ON (reactivate fuel pump), and check for fuel leakage.
6. Start engine and check for fuel leakage.
7. Read the indication of fuel pressure gauge. • During fuel pressure check, check for fuel leakage from fuelconnection every 3 minutes.
BBIA0380E
BBIA0390E
Revision: March 2010 2008 QX56

FUEL PRESSUREEC-495
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8. If result is unsatisfactory, go to next step.
9. Check the following.
• Fuel hoses and fuel tubes for clogging
• Fuel filter for clogging
• Fuel pump
• Fuel pressure regulator for clogging
If OK, replace fuel pressure regulator.
If NG, repair or replace.
10. Before disconnecting Fuel Pressure Gauge and Fuel Pressure Adapter J-44321-6, release fuel pressure
to zero. Refer to "FUEL PRESSURE RELEASE". At idling:
Approximately 350 kPa (3.57 kg/cm
2, 51 psi)
Revision: March 2010 2008 QX56