2005 INFINITI QX4 fuel pressure

DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-251
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Revision: October 20052005 QX56
4. CHECK FUEL PRESSURE
1. Release fuel pressure to zero. Refer to EC-93, "
FUEL PRESSURE RELEASE" .
2. Install fuel pressure gauge and check fuel pressure. Refer to EC-94, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to EC-637, "FUEL PUMP CIRCUIT" .)

Fuel pressure regulator (Refer to EC-94, "FUEL PRESSURE CHECK" .)
>> Repair or replace.
6. CHECK MASS AIR FLOW SENSOR
With CONSULT-II
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-II.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
OK or NG
OK >> GO TO 7.
NG >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to EC-174, "
DTC P0101 MAF SENSOR" . At idling: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm
3.0 - 9.0 g·m/sec: at idling
9.0 - 28.0 g·m/sec: at 2,500 rpm

DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
EC-271
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Revision: October 20052005 QX56
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
PFP:00000
On Board Diagnosis LogicUBS00L0T
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crank-
shaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the 1st trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to over-
heating, the MIL will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions
for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.
If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on.
If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only
light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sen-
sor signal every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
DTC Confirmation ProcedureUBS00L0U
CAUTION:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driv-
ing.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
Sensor Input signal to ECM ECM function
Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0300
0300Multiple cylinder misfire
detectedMultiple cylinder misfire.

Improper spark plug

Insufficient compression

Incorrect fuel pressure

The injector circuit is open or shorted

Fuel injector

Intake air leak

The ignition signal circuit is open or
shorted

Lack of fuel

Signal plate

Air fuel ratio (A/F) sensor 1

Incorrect PCV hose connection P0301
0301No.1 cylinder misfire
detectedNo. 1 cylinder misfires.
P0302
0302No. 2 cylinder misfire
detectedNo. 2 cylinder misfires.
P0303
0303No. 3 cylinder misfire
detectedNo. 3 cylinder misfires.
P0304
0304No. 4 cylinder misfire
detectedNo. 4 cylinder misfires.
P0305
0305No. 5 cylinder misfire
detectedNo. 5 cylinder misfires.
P0306
0306No. 6 cylinder misfire
detectedNo. 6 cylinder misfires.
P0307
0307No. 7 cylinder misfire
detectedNo. 7 cylinder misfires.
P0308
0308No. 8 cylinder misfire
detectedNo. 8 cylinder misfires.

EC-274Revision: October 2005
DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
2005 QX56
5. CHECK FUNCTION OF IGNITION COIL-I
CAUTION:
Do the following procedure in the place where ventilation is good without the combustible.
1. Turn ignition switch OFF.
2. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
NOTE:
Do not use CONSULT-II to release fuel pressure, or fuel pres-
sure applies again during the following procedure.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel
pressure.
5. Turn ignition switch OFF.
6. Remove all ignition coil harness connectors to avoid the electri-
cal discharge from the ignition coils.
7. Remove ignition coil and spark plug of the cylinder to be
checked.
8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
9. Connect spark plug and harness connector to ignition coil.
10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm
between the edge of the spark plug and grounded metal portion
as shown in the figure.
11. Crank engine for about 3 seconds, and check whether spark is
generated between the spark plug and the grounded metal por-
tion.
CAUTION:

Do not approach to the spark plug and the ignition coil
within 50cm. Be careful not to get an electrical shock
while checking, because the electrical discharge voltage
becomes 20kV or more.

It might cause to damage the ignition coil if the gap of more than 17 mm is taken.
NOTE:
When the gap is less than 13 mm, the spark might be generated even if the coil is malfunctioning.
OK or NG
OK >> GO TO 9.
NG >> GO TO 6.
6. CHECK FUNCTION OF IGNITION COIL-II
1. Turn ignition switch OFF.
2. Disconnect spark plug and connect a known-good spark plug.
3. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded metal portion.
OK or NG
OK >> GO TO 7.
NG >> Check ignition coil, power transistor and their circuits. Refer to EC-619, "
IGNITION SIGNAL" . Spark should be generated.
BBIA0380E
PBIB2325E
Spark should be generated.

DTC P0300 - P0308 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-
FIRE
EC-275
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Revision: October 20052005 QX56
7. CHECK SPARK PLUG
Check the initial spark plug for fouling, etc.
OK or NG
OK >> Replace spark plug(s) with standard type one(s). For
spark plug type, refer to EM-27, "
SPARK PLUG (PLATI-
NUM-TIPPED TYPE)" .
NG >> 1. Repair or clean spark plug.
2. GO TO 8.
8. CHECK FUNCTION OF IGNITION COIL-III
1. Reconnect the initial spark plugs.
2. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded portion.
OK or NG
OK >>INSPECTION END
NG >> Replace spark plug(s) with standard type one(s). For spark plug type, refer to MA-18, "
Changing
Spark Plugs" .
9. CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-58, "
CHECKING COMPRESSION PRESSURE" .
OK or NG
OK >> GO TO 10.
NG >> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
10. CHECK FUEL PRESSURE
1. Install all removed parts.
2. Release fuel pressure to zero. Refer to EC-93, "
FUEL PRESSURE RELEASE" .
3. Install fuel pressure gauge and check fuel pressure. Refer to EC-94, "
FUEL PRESSURE CHECK" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 11.
11 . DETECT MALFUNCTIONING PART
Check the following.

Fuel pump and circuit (Refer to EC-637, "FUEL PUMP CIRCUIT" .)

Fuel pressure regulator (Refer to EC-94, "FUEL PRESSURE CHECK" .)

Fuel lines

Fuel filter for clogging
>> Repair or replace.
SEF 1 56 I
Spark should be generated.
At idle: Approximately 350 kPa (3.57 kg/cm
2 , 51 psi)

DTC P0420, P0430 THREE WAY CATALYST FUNCTION
EC-301
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Revision: October 20052005 QX56
5. CHECK INJECTORS
1. Stop engine and then turn ignition switch ON.
2. Check voltage between ECM terminals 21, 22, 23, 40, 41, 42,
44, 63 and ground with CONSULT-II or tester.
Refer to Wiring Diagram for Injectors, EC-632, "
Wiring Diagram"
.
OK or NG
OK >> GO TO 6.
NG >> Perform EC-633, "
Diagnostic Procedure" .
6. CHECK FUNCTION OF IGNITION COIL-I
CAUTION:
Do the following procedure in the place where ventilation is good without the combustible.
1. Turn ignition switch OFF.
2. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
NOTE:
Do not use CONSULT-II to release fuel pressure, or fuel pres-
sure applies again during the following procedure.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel
pressure.
5. Turn ignition switch OFF.
6. Remove all ignition coil harness connectors to avoid the electri-
cal discharge from the ignition coils.
7. Remove ignition coil and spark plug of the cylinder to be
checked.
8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
9. Connect spark plug and harness connector to ignition coil.
10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm
between the edge of the spark plug and grounded metal portion
as shown in the figure.
11. Crank engine for about 3 seconds, and check whether spark is
generated between the spark plug and the grounded metal por-
tion.
CAUTION:

Do not approach to the spark plug and the ignition coil
within 50cm. Be careful not to get an electrical shock
while checking, because the electrical discharge voltage
becomes 20kV or more.

It might cause to damage the ignition coil if the gap of more than 17 mm is taken.
NOTE:
When the gap is less than 13 mm, the spark might be generated even if the coil is malfunctioning.
OK or NG
OK >> GO TO 10.
NG >> GO TO 7.Battery voltage should exist.
PBIB1527E
Spark should be generated.
BBIA0380E
PBIB2325E

DTC P0441 EVAP CONTROL SYSTEM
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Revision: October 20052005 QX56
WITH CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and let it idle for at least 70 seconds.
4. Select “PURG FLOW P0441” of “EVAPORATIVE SYSTEM” in “DTC CONFIRMATION” mode with CON-
SULT-II.
5. Touch “START”.
If “COMPLETED” is displayed, go to step 7.
6. When the following conditions are met, “TESTING” will be displayed on the CONSULT-II screen. Maintain
the conditions continuously until “TESTING” changes to “COMPLETED”. (It will take at least 35 seconds.)
If “TESTING” is not changed for a long time, retry from step 2.
7. Make sure that “OK” is displayed after touching “SELF-DIAG RESULTS”. If “NG” is displayed, refer to EC-
306, "Diagnostic Procedure" .
Overall Function CheckUBS00H4M
Use this procedure to check the overall monitoring function of the EVAP control system purge flow monitoring.
During this check, a 1st trip DTC might not be confirmed.
WITH GST
1. Lift up drive wheels.
2. Start engine (VDC switch OFF) and warm it up to normal operating temperature.
3. Turn ignition switch OFF, wait at least 10 seconds.
4. Start engine and wait at least 70 seconds.
5. Set voltmeter probes to ECM terminals 32 (EVAP control system
pressure sensor signal) and ground.
6. Check EVAP control system pressure sensor value at idle speed
and note it.
7. Establish and maintain the following conditions for at least 1
minute.
8. Verify that EVAP control system pressure sensor value stays 0.1V less than the value at idle speed (mea-
sured at step 6) for at least 1 second.
Selector lever Suitable position
VHCL SPEED SE 32 - 120 km/h (20 - 75 MPH)
ENG SPEED 500 - 3,000 rpm
B/FUEL SCHDL 1.0 - 12.0 msec
COOLAN TEMP/S 70 - 100°C (158 - 212°F)
PBIB0826E
Air conditioner switch ON
Headlamp switch ON
Rear window defogger switch ON
Engine speed Approx. 3,000 rpm
Gear position Any position other than P, N or R
PBIB11 09 E

DTC P0442 EVAP CONTROL SYSTEM
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Revision: October 20052005 QX56
DTC P0442 EVAP CONTROL SYSTEMPFP:14950
On Board Diagnosis LogicUBS00H4O
This diagnosis detects leaks in the EVAP purge line using engine intake manifold vacuum.
If pressure does not increase, the ECM will check for leaks in the line between the fuel tank and EVAP canister
purge volume control solenoid valve, under the following “Vacuum test” conditions.
The EVAP canister vent control valve is closed to shut the EVAP purge line off. The EVAP canister purge vol-
ume control solenoid valve will then be opened to depressurize the EVAP purge line using intake manifold
vacuum. After this occurs, the EVAP canister purge volume control solenoid valve will be closed.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0442
0442EVAP control system
small leak detected
(negative pressure)EVAP control system has a leak, EVAP
control system does not operate prop-
erly.

Incorrect fuel tank vacuum relief valve

Incorrect fuel filler cap used

Fuel filler cap remains open or fails to close.

Foreign matter caught in fuel filler cap.

Leak is in line between intake manifold and
EVAP canister purge volume control solenoid
valve.

Foreign matter caught in EVAP canister vent
control valve.

EVAP canister or fuel tank leaks

EVAP purge line (pipe and rubber tube) leaks

EVAP purge line rubber tube bent

Loose or disconnected rubber tube

EVAP canister vent control valve and the circuit

EVAP canister purge volume control solenoid
valve and the circuit

Fuel tank temperature sensor

O-ring of EVAP canister vent control valve is
missing or damaged

EVAP canister is saturated with water

EVAP control system pressure sensor

Fuel level sensor and the circuit

Refueling EVAP vapor cut valve

ORVR system leaks
PBIB1026E

EC-316Revision: October 2005
DTC P0442 EVAP CONTROL SYSTEM
2005 QX56
13. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE OPERATION
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Stop engine.
3. Disconnect vacuum hose to EVAP canister purge volume control solenoid valve at EVAP service port.
4. Start engine and let it idle for at least 80 seconds.
5. Check vacuum hose for vacuum when revving engine up to 2,000 rpm.
OK or NG
OK >> GO TO 16.
NG >> GO TO 14.
14. CHECK VACUUM HOSE
Check vacuum hoses for clogging or disconnection. Refer to EC-114, "
Vacuum Hose Drawing" .
OK or NG
OK >> GO TO 15.
NG >> Repair or reconnect the hose.
15. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Refer to EC-323, "
Component Inspection" .
OK or NG
OK >> GO TO 16.
NG >> Replace EVAP canister purge volume control solenoid valve.
16. CHECK FUEL TANK TEMPERATURE SENSOR
Refer to EC-258, "
Component Inspection" .
OK or NG
OK >> GO TO 17.
NG >> Replace fuel level sensor unit.
17. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR
Refer to EC-334, "
Component Inspection" .
OK or NG
OK >> GO TO 18.
NG >> Replace EVAP control system pressure sensor.
18. CHECK EVAP PURGE LINE
Check EVAP purge line (pipe, rubber tube, fuel tank and EVAP canister) for cracks or improper connection.
Refer to EC-33, "
EVAPORATIVE EMISSION LINE DRAWING" .
OK or NG
OK >> GO TO 19.
NG >> Repair or reconnect the hose.
19. CLEAN EVAP PURGE LINE
Clean EVAP purge line (pipe and rubber tube) using air blower.
>> GO TO 20. Vacuum should exist.