2001 INFINITI QX4 check engine

5 CHECK IGNITION SPARK
1. Disconnect ignition wire from spark plug.
2. Connect a known good spark plug to the ignition wire.
3. Place end of spark plug against a suitable ground and crank engine.
4. Check for spark.
SEF575Q
OK or NG
OK©GO TO 6.
NG©Check ignition coil, power transistor and their circuits. Refer to ªDTC P1320 IGNITION
SIGNALº, EC-499
6 CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
SEF156I
OK or NG
OK©GO TO 7.
NG©Repair or replace spark plug(s) with standard type one(s). For spark plug type, refer to
MA-13, ªENGINE MAINTENANCEº.
7 CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-14, ªMeasurement of Compression Pressureº.
Standard:
1,275 kPa (13.0 kg/cm
2, 185 psi)/300 rpm
Minimum:
981 kPa (10.0 kg/cm
2, 142 psi)/300 rpm
Difference between each cylinder:
98 kPa (1.0 kg/cm
2, 14 psi)/300 rpm
OK or NG
OK©GO TO 8.
NG©Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
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DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-323

11 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªMANU TRIGº and ªHI SPEEDº in ªDATA MONITORº mode with CONSULT-II, and select ªHO2S1 (B1)/(B2)º and
ªHO2S1 MNTR (B1)/(B2)º.
3. Hold engine speed at 2,000 rpm under no load during the following steps.
4. Touch ªRECORDº on CONSULT-II screen.
SEF967Y
5. Check the following.
IªHO2S1 MNTR (B1)/(B2)º in ªDATA MONITORº mode changes from ªRICHº to ªLEANº to ªRICHº 5 times in 10 seconds.
5 times (cycles) are counted as shown left:
SEF647Y
IªHO2S1 (B1)/(B2)º voltage goes above 0.6V at least once.
IªHO2S1 (B1)/(B2)º voltage goes below 0.3V at least once.
IªHO2S1 (B1)/(B2)º voltage never exceeds 1.0V.
SEF648Y
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 14.
NG©GO TO 13.
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DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-325

12 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 63 (HO2S1 bank 1 right signal) or 62 (HO2S1 bank 2 left signal) and
engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEF967XA
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©GO TO 14.
NG©GO TO 13.
13 REPLACE HEATED OXYGEN SENSOR 1 (FRONT)
1. Turn ignition switch ªOFFº.
2. Check heated oxygen sensor 1 (front) harness protector color.
SEF505Y
©Replace malfunctioning heated oxygen sensor 1 (front).
DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-326

14 CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check mass air flow sensor signal in ªDATA MONITORº mode with CONSULT-II.
2.0 - 6.0 g´m/sec: at idling
7.0 - 20.0 g´m/sec: at 2,500 rpm
With GST
Check mass air flow sensor signal in MODE 1 with GST.
2.0 - 6.0 g´m/sec: at idling
7.0 - 20.0 g´m/sec: at 2,500 rpm
OK or NG
OK©GO TO 15.
NG©Check connectors for rusted terminals or loose connections in the mass air flow sensor
circuit or engine grounds. Refer to EC-150.
15 CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in ªSymptom Matrix Chartº, EC-118.
OK or NG
OK©GO TO 16.
NG©Repair or replace.
16 ERASE THE 1ST TRIP DTC
Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to EC-72.
Some tests may cause a 1st trip DTC to be set.
©GO TO 17.
17 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
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DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-327

Diagnostic ProcedureNBEC0190
1 CHECK KNOCK SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-I
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check resistance between ECM terminal 93 and engine ground.
NOTE:
It is necessary to use an ohmmeter which can measure more than 10 MW.
SEF321X
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 2.
2 CHECK KNOCK SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-II
1. Disconnect knock sensor harness connector.
2. Check harness continuity between ECM terminal 93 and knock sensor terminal 2. Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F19, F116
IHarness for open or short between ECM and knock sensor
©Repair open circuit or short to ground or short to power in harness or connectors.
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DTC P0325 KNOCK SENSOR (KS)
Diagnostic Procedure
EC-331

4 CHECK KNOCK SENSOR
Check resistance between knock sensor terminal 2 and ground.
NOTE:
It is necessary to use an ohmmeter which can measure more than 10 MW.
SEF976Y
CAUTION:
Do not use any knock sensors that have been dropped or physically damaged. Use only new ones.
OK or NG
OK©GO TO 8.
NG©Replace knock sensor.
5 RETIGHTEN GROUND SCREWS
Loose and retighten engine ground screws.
SEF959Y
©GO TO 6.
6 CHECK KNOCK SENSOR SHIELD CIRCUIT FOR OPEN AND SHORT
1. Disconnect harness connectors F19, F116.
2. Check harness continuity between harness connector F19 terminal 1 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 8.
NG©GO TO 7.
7 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F19, F116
IHarness for open or short between harness connector F19 and engine ground
©Repair open circuit or short to power in harness or connectors.
DTC P0325 KNOCK SENSOR (KS)
Diagnostic Procedure (Cont'd)
EC-332

Diagnostic ProcedureNBEC0196
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF959Y
©GO TO 2.
2 CHECK CKPS (POS) POWER SUPPLY CIRCUIT
1. Disconnect harness connectors E132, E135.
SEF978Y
2. Check voltage between harness connector E135 terminal 6 and ground with CONSULT-II or tester.
SEF979Y
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©GO TO 3.
DTC P0335 CRANKSHAFT POSITION SENSOR (CKPS) (POS)
Diagnostic Procedure
EC-338

3 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E132, E135
IHarness for open or short between ECM and crankshaft position sensor (POS)
IHarness for open or short between ECM relay and crankshaft position sensor (POS)
©Repair open circuit or short to ground or short to power in harness or connectors.
4 CHECK CKPS (POS) GROUND CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between harness connector E135 terminal 1 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
2. Also check harness for short to power.
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E132, E135
IHarness connectors E116, M114
IHarness connectors M32, F23
IHarness for open between crankshaft position sensor (POS) and ground.
©Repair open circuit or short to ground or short to power in harness or connectors.
6 CHECK CKPS (POS) INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 85 and harness connector E135 terminal 5.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 8.
NG©GO TO 7.
7 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E132, E135
IHarness connectors E116, M114
IHarness connectors M32, F23
IHarness for open or short between ECM and crankshaft position sensor (POS)
©Repair open circuit or short to ground or short to power in harness or connectors.
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DTC P0335 CRANKSHAFT POSITION SENSOR (CKPS) (POS)
Diagnostic Procedure (Cont'd)
EC-339