2001 INFINITI QX4 timing

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b) Connect No. 1 ignition coil and No. 1 spark plug with suitable
high-tension wire as shown, and attach timing light clamp to
this wire.
c) Check ignition timing.
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Idle Speed/Ignition Timing/Idle Mixture Ratio
Adjustment
NBEC0028PREPARATIONNBEC0028S011) Make sure that the following parts are in good order.
IBattery
IIgnition system
IEngine oil and coolant levels
IFuses
IECM harness connector
IVacuum hoses
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BASIC SERVICE PROCEDURE
How to Check Idle Speed and Ignition Timing (Cont'd)
EC-43

IAir intake system
(Oil filler cap, oil level gauge, etc.)
IFuel pressure
IEngine compression
IThrottle valve
IEvaporative emission system
2) On air conditioner equipped models, checks should be carried out while the air conditioner is ªOFFº.
3) On automatic transmission equipped models, when checking idle rpm, ignition timing and mixture ratio,
checks should be carried out while shift lever is in ªNº position.
4) When measuring ªCOº percentage, insert probe more than 40 cm (15.7 in) into tail pipe.
5) Turn off headlamps, heater blower, rear defogger.
6) Keep front wheels pointed straight ahead.
7) Make the check after the cooling fan has stopped.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-44

Overall Inspection SequenceNBEC0028S0101
SEC141C
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BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-45

INSPECTION PROCEDURE=NBEC0028S02
1 INSPECTION START
1. Visually check the following:
IAir cleaner clogging
IHoses and ducts for leaks
IElectrical connectors
IGasket
IThrottle valve and throttle position sensor operation
2. Start engine and warm it up until engine coolant temperature indicator points to the middle of gauge.
Ensure engine stays below 1,000 rpm.
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3. Open engine hood and run engine at about 2,000 rpm for about 2 minutes under no-load.
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4. Make sure that no DTC is displayed with CONSULT-II or GST.
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 REPAIR OR REPLACE
Repair or replace components as necessary according to corresponding ªDiagnostic Procedureº.
©GO TO 3.
3 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 12.
NG©GO TO 4.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-46

4 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 5.
INCMP©1. Follow the construction of ªIdle Air Volume Leaningº.
2. GO TO 4.
5 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 10.
NG©GO TO 6.
6 REPLACE IACV-AAC VALVE
Replace IACV-AAC valve.
©GO TO 7.
7 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 8.
INCMP©1. Follow the construction of ªIdle Air Volume Learningº.
2. GO TO 4.
8 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 10.
NG©GO TO 9.
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BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-47

9 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 4.
10 CHECK IGNITION TIMING
1. Start engine and warm it up to normal operating temperature.
2. Check ignition timing at idle using a timing light.
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15ɱ5É BTDC (in ªPº or ªNº position)
OK or NG
OK©GO TO 18.
NG©GO TO 11.
11 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-29, ªInstallationº.
OK or NG
OK©GO TO 9.
NG©1. Repair the timing chain installation.
2. GO TO 4.
12 CHECK IGNITION TIMING
1. Start engine and let it idle.
2. Check ignition timing at idle using a timing light.
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15ɱ5É BTDC (in ªPº or ªNº position)
OK or NG
OK©GO TO 18.
NG©GO TO 13.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-48

13 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 14.
INCMP©1. Follow the construction of ªIdle Air volume Learningº.
2. GO TO 13.
14 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 16.
NG©GO TO 15.
15 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 13.
16 CHECK IGNITION TIMING AGAIN
Check ignition timing again. Refer to Test No. 12.
OK or NG
OK©GO TO 18.
NG©GO TO 17.
17 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-29, ªInstallationº.
OK or NG
OK©GO TO 15.
NG©1. Repair the timing chain installation.
2. GO TO 13.
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BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-49

18 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.
With CONSULT-II©GO TO 19.
Without CONSULT-II©GO TO 20.
19 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 2) SIGNAL
With CONSULT-II
1. Run engine at about 2,000 rpm for about 2 minutes under no-load.
2. See ªHO2S1 MNTR (B2)º in ªDATA MONITORº mode.
3. Running engine at 2,000 rpm under no-load (engine is warmed up to normal operating temperature.), check that the
monitor fluctuates between ªLEANº and ªRICHº more than 5 times during 10 seconds.
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OK or NG
OK©GO TO 23.
NG (Monitor does not
fluctuate.)©GO TO 28.
NG (Monitor fluctuates
less than 5 times.)©GO TO 21.
20 CHECK HEATED OXYGEN SENSOR 1 (FRONT) (BANK 2) SIGNAL
Without CONSULT-II
1. Run engine at about 2,000 rpm for about 2 minutes under no-load.
2. Set voltmeter probe between ECM terminal 62 and ground.
3. Make sure that the voltage fluctuates between 0 - 0.3V and 0.6 - 1.0V more than 5 times during 10 seconds at 2,000
rpm.
1 time: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V
2 times: 0 - 0.3V®0.6 - 1.0V®0 - 0.3V®0.6 - 1.0V®0 - 0.3V
OK or NG
OK©GO TO 23.
NG (Voltage does not
fluctuate.)©GO TO 28.
NG (Voltage fluctuates
less than 5 times.)©GO TO 21.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-50