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Home >> Nissan-Datsun >> 2005 >> Pathfinder LE, 4WD >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> Basic Service Procedure >> Idle Mixture Ratio Adjustment >> Detailed Procedure

Detailed Procedure

  1. INSPECTION START 
    1. Check service records for any recent repairs that may indicate a related malfunction, or a current need for scheduled maintenance.
    2. Open engine hood and check the following:
      • Harness connectors for improper connections
      • Wiring harness for improper connections, pinches and cut
      • Vacuum hoses for splits, kinks and improper connections
      • Hoses and ducts for leaks
      • Air cleaner clogging
      • Gasket
      Fig 1: Checking Harness Connectors And Wiring Harness For Improper Connections
      G02431501Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Confirm that electrical or mechanical loads are not applied.
      • Headlamp switch is OFF.
      • Air conditioner switch is OFF.
      • Rear window defogger switch is OFF.
      • Steering wheel is in the straight-ahead position, etc.
    4. Start engine and warm it up until engine coolant temperature indicator points the middle of gauge.

      Ensure engine stays below 1, 000 rpm.

      Fig 2: Identifying Engine Coolant Temperature Indicator
      G02431502Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Run engine at about 2, 000 rpm for about 2 minutes under no-load.
    6. Make sure that no DTC is displayed with CONSULT-II or GST.

    OK or NG 

    • OK: GO TO  3.
    • NG: GO TO 2.
    Fig 3: Identifying Tachometer Display (2, 000 RPM)
    G02431503Courtesy of NISSAN MOTOR CO., U.S.A.
  2. REPAIR OR REPLACE 

    Repair or replace components as necessary according to corresponding Diagnostic Procedure.

    • GO TO 3.
  3. CHECK TARGET IDLE SPEED 

    With CONSULT-II 

    1. Run engine at about 2, 000 rpm for about 2 minutes under no-load.
    2. Rev engine (2, 000 to 3, 000 rpm) two or three times under no-load, then run engine at idle speed for about 1 minute
      Fig 4: Identifying Tachometer Display (RPM Decreasing)
      G02431504Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Read idle speed in "DATA MONITOR" mode with CONSULT-II. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 
      Fig 5: CONSULT-II Display - Data Monitor Mode
      G02431505Courtesy of NISSAN MOTOR CO., U.S.A.

    Without CONSULT-II 

    1. Run engine at about 2, 000 rpm for about 2 minutes under no-load.
    2. Rev engine (2, 000 to 3, 000 rpm) two or three times under no-load, then run engine at idle speed for about 1 minute.
    3. Check idle speed. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 

    OK or NG 

    • OK: GO TO  10.
    • NG: GO TO 4.
  4. PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING 
    1. Stop engine.
    2. Perform ACCELERATOR PEDAL RELEASED POSITION LEARNING .
      • GO TO 5.
  5. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING 

    Perform THROTTLE VALVE CLOSED POSITION LEARNING .

    • GO TO 6.
  6. PERFORM IDLE AIR VOLUME LEARNING 

    Perform IDLE AIR VOLUME LEARNING .

    Is Idle Air Volume Learning carried out successfully? 

    Yes or No 

    • Yes: GO TO 7.
    • No:
      1. Follow the instruction of Idle Air Volume Learning.
      2. GO TO 4.
  7. CHECK TARGET IDLE SPEED AGAIN 

    With CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Read idle speed in "DATA MONITOR" mode with CONSULT-II. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 

    Without CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Check idle speed. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 

    OK or NG 

    • OK: GO TO  10.
    • NG: GO TO 8.
    Fig 6: CONSULT-II Display - Data Monitor Mode
    G02431506Courtesy of NISSAN MOTOR CO., U.S.A.
  8. DETECT MALFUNCTIONING PART 

    Check the following.

    OK or NG 

    • OK: GO TO 9.
    • NG:
      1. Repair or replace.
      2. GO TO  4.
  9. CHECK ECM FUNCTION 
    1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but this is a rare case.)
    2. Perform initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs. Refer to ECM RE-COMMUNICATING FUNCTION .
      • GO TO 4.
  10. CHECK IGNITION TIMING 
    1. Run engine at idle.
    2. Check ignition timing with a timing light. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 15 +/- 5° BTDC (in P or N position)  . Refer to Fig 7.

    OK or NG 

    • OK (With CONSULT-II): GO TO  19.
    • OK (Without CONSULT-II): GO TO  20.
    • NG: GO TO 11.
    Fig 7: Checking Ignition Timing
    G02431507Courtesy of NISSAN MOTOR CO., U.S.A.
  11. PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING 
    1. Stop engine.
    2. Perform ACCELERATOR PEDAL RELEASED POSITION LEARNING .
      • GO TO 12.
  12. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING 

    Perform THROTTLE VALVE CLOSED POSITION LEARNING .

    • GO TO 13.
  13. PERFORM IDLE AIR VOLUME LEARNING 

    Perform IDLE AIR VOLUME LEARNING .

    Is Idle Air Volume Learning carried out successfully? 

    Yes or No 

    • Yes: GO TO 14.
    • No:
      1. Follow the instruction of Idle Air Volume Learning.
      2. GO TO 4.
  14. CHECK TARGET IDLE SPEED AGAIN 

    With CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Read idle speed in "DATA MONITOR" mode with CONSULT-II. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 

    Without CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Check idle speed. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 625 +/- 50 rpm (in P or N position) 

    OK or NG 

    • OK: GO TO 15.
    • NG: GO TO  17.
    Fig 8: CONSULT-II Display - Data Monitor Mode
    G02431508Courtesy of NISSAN MOTOR CO., U.S.A.
  15. CHECK IGNITION TIMING AGAIN 
    1. Run engine at idle.
    2. Check ignition timing with a timing light. Refer to IDLE SPEED AND IGNITION TIMING CHECK .
      • 15 +/- 5° BTDC (in P or N position)  . Refer to Fig 9.

    OK or NG 

    • OK (With CONSULT-II): GO TO  19.
    • OK (Without CONSULT-II): GO TO  20.
    • NG: GO TO 16.
    Fig 9: Checking Ignition Timing
    G02431509Courtesy of NISSAN MOTOR CO., U.S.A.
  16. CHECK TIMING CHAIN INSTALLATION 

    Check timing chain installation. Refer to TIMING CHAIN .

    OK or NG 

    • OK: GO TO 17.
    • NG:
      1. Repair the timing chain installation.
      2. GO TO  4.
  17. DETECT MALFUNCTIONING PART 

    Check the following.

    OK or NG 

    • OK: GO TO 18.
    • NG:
      1. Repair or replace.
      2. GO TO  4.
  18. CHECK ECM FUNCTION 
    1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but this is a rare case.)
    2. Perform initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs. Refer to ECM RE-COMMUNICATING FUNCTION .
      • GO TO  4.
  19. CHECK AIR FUEL RATIO (A/F) SENSOR 1 FUNCTION 

    With CONSULT-II 

    1. Turn ignition switch OFF and wait at a least 10 seconds.
    2. Start engine and warm it up to normal operating temperature.
    3. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in D position.
      NOTE: Keep the accelerator pedal as steady as possible during the cruising.
    4. Then release the accelerator pedal fully until the vehicle speed decreases to 50 km/h (30 MPH).
      NOTE: Never apply brake during releasing the accelerator pedal.
    5. Repeat steps 3 to 4 for 5 times.
    6. Stop the vehicle and connect CONSULT-II to the vehicle.
    7. Make sure that no (1st trip) DTC is displayed in "SELF-DIAG RESULTS" mode.

    OK or NG 

    • OK: INSPECTION END 
    • NG: GO TO 21.
  20. CHECK AIR FUEL RATIO (A/F) SENSOR 1 FUNCTION 

    With GST 

    1. Turn ignition switch OFF and wait at a least 10 seconds.
    2. Start engine and warm it up to normal operating temperature.
    3. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in D position.
      NOTE: Keep the accelerator pedal as steady as possible during the cruising.
    4. Then release the accelerator pedal fully until the vehicle speed decreases to 50 km/h (30 MPH).
      NOTE: Never apply brake during releasing the accelerator pedal.
    5. Repeat steps 3 to 4 for 5 times.
    6. Stop the vehicle and connect GST to the vehicle.
    7. Make sure that no (1st trip) DTC is displayed.

    OK or NG 

    • OK: INSPECTION END 
    • NG: GO TO 21.
  21. CHECK AIR FUEL RATIO (A/F) SENSOR 1 HARNESS 
    1. Turn ignition switch OFF and disconnect battery negative cable.
    2. Disconnect ECM harness connector.
    3. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
    4. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
      Fig 10: A/F Sensor 1 Terminals And ECM Terminals Reference Chart
      G02431510Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should exist. 
    5. Also check harness for short to ground and short to power.

    OK or NG 

    • OK: GO TO 22.
    • NG:
      1. Repair open circuit or short to ground or short to power in harness or connectors between ECM and air fuel ratio (A/F) sensor 1.
      2. GO TO  4.
  22. PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING 
    1. Reconnect ECM harness connector.
    2. Perform ACCELERATOR PEDAL RELEASED POSITION LEARNING .
      • GO TO 23.
  23. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING 

    Perform THROTTLE VALVE CLOSED POSITION LEARNING ".

    • GO TO 24.
  24. PERFORM IDLE AIR VOLUME LEARNING 

    Refer to IDLE AIR VOLUME LEARNING .

    Is Idle Air Volume Learning carried out successfully? 

    Yes or No 

    • Yes (With CONSULT-II): GO TO 25.
    • Yes (Without CONSULT-II): GO TO  26.
    • No:
      1. Follow the instruction of Idle Air Volume Learning.
      2. GO TO  4.
  25. CHECK CO% 

    With CONSULT-II 

    1. Start engine and warm it up until engine coolant temperature indicator points the middle of gauge.
    2. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
    3. Select "ENG COOLANT TEMP" in "ACTIVE TEST" mode.
    4. Set "ENG COOLANT TEMP" to 5°C (41°F) by touching "DWN" and "Qd".
    5. Start engine and rev it (2, 000 to 3, 000 rpm) two or three times under no load, then run engine at idle speed.
    6. Check CO%.
      • Idle CO: 0.7 - 9.9% and engine runs smoothly. 

    OK or NG 

    • OK: GO TO  28.
    • NG: GO TO  27.
    Fig 11: CONSULT-II Display - Active Test Mode
    G02431511Courtesy of NISSAN MOTOR CO., U.S.A.
  26. CHECK CO% 

    Without CONSULT-II 

    1. Start engine and warm it up until engine coolant temperature indicator points to the middle of gauge.
    2. Turn ignition switch OFF.
    3. Disconnect engine coolant temperature sensor harness connector.
    4. Connect a resistor (4.4 kΩ) between terminals of engine coolant temperature sensor harness connector. Refer to Fig 12.
    5. Start engine and rev it (2, 000 to 3, 000 rpm) two or three times under no load, then run engine at idle speed.
    6. Check CO%.
      • Idle CO: 0.7 - 9.9% and engine runs smoothly. 
    7. After checking CO%, turn ignition switch OFF, disconnect the resistor from the terminals of engine coolant temperature sensor harness connector, and then connect engine coolant temperature sensor harness connector to engine coolant temperature sensor.

    OK or NG 

    • OK: GO TO  28.
    • NG: GO TO 27.
    Fig 12: Connecting Resistor Between Terminals Of Engine Coolant Temperature Sensor Harness Connector
    G02431512Courtesy of NISSAN MOTOR CO., U.S.A.
  27. RECONNECT AIR FUEL RATIO (A/F) SENSOR 1 HARNESS CONNECTOR 
    1. Turn ignition switch OFF.
    2. Reconnect air fuel ratio (A/F) sensor 1 harness connector.
      • GO TO 31.
  28. REPLACE AIR FUEL RATIO (A/F) SENSOR 1 
    1. Stop engine.
    2. Replace air fuel ratio (A/F) sensor 1 on the malfunctioning bank.
      • With CONSULT-II: GO TO 29.
      • Without CONSULT-II: GO TO  30.
  29. CHECK AIR FUEL RATIO (A/F) SENSOR 1 FUNCTION 

    With CONSULT-II 

    1. Turn ignition switch OFF and wait at a least 10 seconds.
    2. Start engine and warm it up to normal operating temperature.
    3. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in D position.
      NOTE: Keep the accelerator pedal as steady as possible during the cruising.
    4. Then release the accelerator pedal fully until the vehicle speed decreases to 50 km/h (30 MPH).
      NOTE: Never apply brake during releasing the accelerator pedal.
    5. Repeat steps 3 to 4 for 5 times.
    6. Stop the vehicle and connect CONSULT-II to the vehicle.
    7. Make sure that no (1st trip) DTC is displayed in "SELF-DIAG RESULTS" mode.

    OK or NG 

    • OK: GO TO  4.
    • NG: GO TO  31.
  30. CHECK AIR FUEL RATIO (A/F) SENSOR 1 FUNCTION 

    With GST 

    1. Turn ignition switch OFF and wait at a least 10 seconds.
    2. Start engine and warm it up to normal operating temperature.
    3. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in D position.
      NOTE: Keep the accelerator pedal as steady as possible during the cruising.
    4. Then release the accelerator pedal fully until the vehicle speed decreases to 50 km/h (30 MPH).
      NOTE: Never apply brake during releasing the accelerator pedal.
    5. Repeat steps 3 to 4 for 5 times.
    6. Stop the vehicle and connect GST to the vehicle.
    7. Make sure that no (1st trip) DTC is displayed.

    OK or NG 

    • OK: GO TO  4.
    • NG: GO TO 31.
  31. DETECT MALFUNCTIONING PART 

    Check the following.

    OK or NG 

    • OK: GO TO  33.
    • NG:
      1. Repair or replace.
      2. GO TO 32.
  32. ERASE UNNECESSARY DTC 

    After this inspection, unnecessary DTC might be displayed.

    Erase the stored memory in ECM and TCM. Refer to HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION  and OBD-II DIAGNOSTIC TROUBLE CODE (DTC) or HOW TO ERASE DTC ".

    • GO TO  4.
  33. CHECK ECM FUNCTION 
    1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but this is a rare case.)
    2. Perform initialization of NVIS (NATS) system and registration of all NVIS (NATS) ignition key IDs. Refer to ECM RE-COMMUNICATING FUNCTION .
      • GO TO  4.