2001 INFINITI QX4 check engine

9 CHECK THROTTLE VALVE OPERATION
1. Remove intake air ducts.
2. Check throttle valve operation when moving throttle drum by hand.
OK or NG
OK©1. Retighten the throttle drum fixing nuts.
2. GO TO 7.
NG©1. Clean the throttle body and throttle valve.
2. GO TO 7.
10 CHECK THROTTLE POSITION SWITCH CLOSED POSITION-I
NOTE:
Always check ignition timing before performing the following.
1. Warm up engine to normal operating temperature.
2. Stop engine.
3. Remove the vacuum hose connected to the throttle opener.
4. Connect suitable vacuum hose to vacuum pump as shown below.
SEF793WA
5. Apply vacuum [more than þ40.0 kPa (þ300 mmHg, þ11.81 inHg)] until the throttle drum is free from the throttle opener
rod.
With CONSULT-II©GO TO 11.
Without CONSULT-II©GO TO 15.
TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-104

17 ADJUSTMENT THROTTLE POSITION SWITCH CLOSED POSITION-II
1. Temporarily tighten sensor body fixing bolts as follows.
IGradually move the sensor body clockwise and stop it when the continuity comes to exist, then temporarily
tighten sensor body fixing bolts.
SEF954Y
2. Make sure two or three times that the continuity exists when the throttle valve is closed and continuity does not exist
when it is opened.
3. Remove 0.05 mm (0.0020 in) feeler gauge then insert 0.15 mm (0.0059 in) feeler gauge.
4. Make sure two or three times that the continuity does not exist when the throttle valve is closed.
5. Tighten throttle position sensor.
6. Check the continuity again.
Continuity does not exist while closing the throttle valve.
OK or NG
OK©GO TO 18.
NG©GO TO 16.
18 RESET THROTTLE POSITION SENSOR IDLE POSITION MEMORY
NOTE:
Always warm up engine to normal operating temperature. If engine is cool, the throttle position sensor idle posi-
tion memory will not be reset correctly.
1. Confirm that proper vacuum is applied. Refer to Test No. 10.
2. Attach blind cap to vacuum port from which vacuum hose to throttle opener was disconnected.
3. Start engine.
4. Warm up engine to normal operating temperature.
5. Stop engine. (Turn ignition switch ªOFFº.)
6. Turn ignition switch ªONº and wait at least 5 seconds.
SEF864V
7. Turn ignition switch ªOFFº and wait at least 10 seconds.
8. Repeat steps 6 and 7, 20 times.
©GO TO 19.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-111

19 CHECK (1ST TRIP) DTC
1. Turn ignition switch ªOFFº.
2. Release vacuum from throttle opener.
3. Remove vacuum pump and vacuum hose from throttle opener.
4. Reinstall original vacuum hose to throttle opener securely.
5. Start engine and warm it up to normal operating temperature.
6. Rev (2,000 to 3,000 rpm) two or three times.
7. Make sure no (1st trip) DTC is displayed with CONSULT-II or GST.
OK or NG
OK©GO TO 21.
NG©GO TO 20.
20 REPAIR MALFUNCTION
Repair or replace components as necessary according to corresponding ªDiagnostic Procedureº.
©GO TO 19.
21 CHECK TARGET IDLE SPEED
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 30.
NG©GO TO 22.
22 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-57.
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 23.
INCMP©1. Follow the construction of ªIdle Air Volume Leaningº.
2. GO TO 22.
TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-112

23 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 28.
NG©GO TO 24.
24 REPLACE IACV-AAC VALVE
Replace IACV-AAC valve.
©GO TO 25.
25 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-57.
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 26.
INCMP©1. Follow the construction of ªIdle Air Volume Learningº.
2. GO TO 22.
26 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 28.
NG©GO TO 27.
27 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of a problem, but this is rarely
the case.)
2. Perform initialization of IVIS (NATS) system and registration of IVIS (NATS) ignition key IDs. Refer to ªIVIS (INFINITI
VEHICLE IMMOBILIZER SYSTEM Ð NATS)º, EC-74.
©GO TO 22.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-113

28 CHECK IGNITION TIMING
1. Start engine and warm it up to normal operating temperature.
2. Check ignition timing at idle using a timing light.
SEF572X
Ignition timing:
15ɱ5É BTDC (in ªPº or ªNº position)
OK or NG
OK©GO TO 36.
NG©GO TO 29.
29 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-29, ªInstallationº.
OK or NG
OK©GO TO 27.
NG©1. Repair the timing chain installation.
2. GO TO 22.
30 CHECK IGNITION TIMING
1. Start engine and let it idle.
2. Check ignition timing at idle using a timing light.
SEF572X
Ignition timing:
15ɱ5É BTDC (in ªPº or ªNº position)
OK or NG
OK©GO TO 36.
NG©GO TO 31.
TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-114

31 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-57.
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 32.
INCMP©1. Follow the construction of ªIdle Air volume Learningº.
2. GO TO 31.
32 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 34.
NG©GO TO 33.
33 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function.
(ECM may be the cause of a problem, but this is rarely the case.)
2. Perform initialization of NVIS (NATS) system and registration of NVIS (NATS) ignition key IDs. Refer to ªNVIS (NISSAN
VEHICLE IMMOBILIZER SYSTEM Ð NATS)º, EC-74.
©GO TO 31.
34 CHECK IGNITION TIMING AGAIN
Check ignition timing again. Refer to Test No. 30.
OK or NG
OK©GO TO 36.
NG©GO TO 35.
35 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-29, ªInstallationº.
OK or NG
OK©GO TO 33.
NG©1. Repair the timing chain installation.
2. GO TO 31.
36 ERASE UNNECESSARY DTC
After this inspection, unnecessary DTC No. might be displayed.
Erase the stored memory in ECM and TCM (Transmission control module).
Refer to ªHow to Erase Emission-Related Diagnostic Informationº, EC-72 and AT-35, ªHOW TO ERASE DTCº.
©INSPECTION END
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-115

DTC Inspection Priority ChartNBEC0039If some DTCs are displayed at the same time, perform inspections one by one based on the following prior-
ity chart.
Priority Detected items (DTC)
1IP0100 Mass air flow sensor
IP0110 Intake air temperature sensor
IP0115 P0125 Engine coolant temperature sensor
IP0120 Throttle position sensor
IP0180 Fuel tank temperature sensor
IP0325 Knock sensor
IP0335 P1336 Crankshaft position sensor (POS)
IP0340 Camshaft position sensor (PHASE)
IP0460 P0461 P0464 P1464 Fuel level sensor
IP0500 Vehicle speed sensor
IP0605 ECM
IP1320 Ignition signal
IP1335 Crankshaft position sensor (REF)
IP1605 A/T diagnosis communication line
IP1706 Park/Neutral position (PNP) switch
2IP0105 Absolute pressure sensor
IP0130-P0134, P0150-P0154 Heated oxygen sensor 1 (front)
IP0135 P0155 Heated oxygen sensor 1 heater (front)
IP0137-P0140, P0157-P0160 Heated oxygen sensor 2 (rear)
IP0141 P0161 Heated oxygen sensor 2 (rear) heater
IP0217 Coolant overtemperature enrichment protection
IP0443 P1444 EVAP canister purge volume control solenoid valve
IP0446 P1446 P1448 EVAP canister vent control valve
IP0450 EVAP control system pressure sensor
IP0510 Closed throttle position switch
IP0705-P0755 P1705 P1760 A/T related sensors, solenoid valves and switches
IP 1111Intake valve timing control solenoid valve
IP1140 Intake valve timing control position sensor
IP1165 Swirl control valve control vacuum check switch
IP1441 EVAP control system (VERY SMALL LEAK)
IP1447 EVAP control system purge flow monitoring
IP1490 P1491 Vacuum cut valve bypass valve
3IP0171 P0172 P0174 P0175 Fuel injection system function
IP0306 - P0300 Misfire
IP0420 P0430 Three way catalyst function
IP0440 P1440 EVAP control system (SMALL LEAK)
IP0455 EVAP control system (GROSS LEAK)
IP0505 IACV-AAC valve
IP0600 A/T communication line
IP0731-P0734 P0744 A/T function
IP1110 Intake valve timing control
IP1130 Swirl control valve control solenoid valve
IP1148 P1168 Closed loop control
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
DTC Inspection Priority Chart
EC-116

SYMPTOM
Reference
section
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
IVIS (INFINITI Vehicle Immobilizer System Ð
NATS)11EC-74 or EL
section
1 - 6: The numbers refer to the order of inspection.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0042Remarks:
ISpecification data are reference values.
ISpecification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show the specification data in
spite of the ignition timing not being adjusted to the specification data. This IGN TIMING monitors the data calculated by the ECM
according to the signals input from the camshaft position sensor and other ignition timing related sensors.
IIf the real-time diagnosis results are NG and the on board diagnostic system results are OK when diagnosing the mass air flow sensor,
first check to see if the fuel pump control circuit is normal.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEED
CKPS´RPM (POS)ITachometer: Connect
IRun engine and compare tachometer indication with the CONSULT-II
value.Almost the same speed as
the CONSULT-II value.
POS COUNTIEngine: Running 179 - 181
MAS A/F SE-B1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 1.2 - 1.8V
2,500 rpm 1.6 - 2.2V
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
HO2S1 (B1)
HO2S1 (B2)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,Approx. 0.6 -
1.0V
HO2S1 MNTR (B1)
HO2S1 MNTR (B2)LEAN+,RICH
Changes more than 5 times
during 10 seconds.
HO2S2 (B1)
HO2S2 (B2)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,Approx. 0.6 -
1.0V
HO2S2 MNTR (B1)
HO2S2 MNTR (B2)LEAN+,RICH
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Matrix Chart (Cont'd)
EC-122