LEMON Manuals: Even more car manuals for everyone
Home >> Infiniti >> 2004 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System >> DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308: Multiple Cylinder Misfire, No. 1 - 8 Cylinder Misfire >> Diagnostic Procedure

Diagnostic Procedure

  1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE 
    1. Start engine and run it at idle speed.
    2. Listen for the sound of the intake air leak.
    3. Check PCV hose connection.

    OK or NG

    OK: GO TO 2.

    NG: Discover air leak location and repair.

  2. CHECK FOR EXHAUST SYSTEM CLOGGING 

    Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.

    OK or NG

    OK: GO TO 3.

    NG: Repair or replace it.

  3. PERFORM POWER BALANCE TEST 

    WITH CONSULT-II 

    1. Perform "POWER BALANCE" in "ACTIVE TEST" mode.
    2. Is there any cylinder which does not produce a momentary engine speed drop?
      Fig 1: Display "POWER BALANCE" In "ACTIVE TEST" Mode
      G02691364Courtesy of NISSAN MOTOR CO., U.S.A.

    Without CONSULT-II 

    When disconnecting each injector harness connector one at a time, is there any cylinder which does not produce a momentary engine speed drop?

    Fig 2: Locating Injector Harness Connectors
    G02691365Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No

    Yes: GO TO 4.

    No: GO TO  7.

  4. CHECK INJECTOR 

    Does each injector make an operating sound at idle?

    Fig 3: Listening To Each Injector Operating Sound
    G02691366Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No

    Yes: GO TO 5.

    No: Check injector(s) and circuit(s). Refer to INJECTOR CIRCUIT .

  5. CHECK IGNITION SPARK 
    1. Turn ignition switch OFF.
    2. Remove ignition coil assembly from rocker cover.
    3. Remove spark plug from ignition coil assembly.
    4. Connect a known-good spark plug to the ignition coil.
    5. Disconnect all injector harness connectors.
    6. Place end of spark plug against a suitable ground and crank engine.
    7. Check for spark.
      Fig 4: Checking Ignition Spark
      G02691367Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    OK: GO TO 6.

    NG: Check ignition coil, power transistor and their circuits. Refer to IGNITION SIGNAL .

  6. CHECK SPARK PLUGS 

    Remove the spark plugs and check for fouling, etc.

    Fig 5: Checking Spark Plugs For Damage
    G02691368Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    OK: GO TO 7.

    NG: Repair or replace spark plug(s) with standard type one(s).

  7. CHECK COMPRESSION PRESSURE 

    Check compression pressure. Refer to CHECKING COMPRESSION PRESSURE .

    CHECKING COMPRESSION PRESSURE

    Standard: 1,520 kPa (15.5 kg/cm2 , 200 psi)/200 RPM
    Minimum: 1,324 kPa (13.5 kg/cm2 , 192 psi)/200 RPM
    Difference between each cylinder: 98 kPa (1.0 kg/cm2 , 14 psi)/200 RPM

    OK or NG

    OK: GO TO 8.

    NG: Check pistons, piston rings, valves, valve seats and cylinder head gaskets.

  8. CHECK FUEL PRESSURE 
    1. Install all removed parts.
    2. Release fuel pressure to zero. Refer to FUEL PRESSURE RELEASE .
    3. Install fuel pressure gauge and check fuel pressure. Refer to FUEL PRESSURE CHECK .

      At idle: Approx. 350 kPa (3.57 kg/cm 2  , 51 psi) 

    OK or NG

    OK: GO TO  10.

    NG: GO TO 9.

  9. DETECT MALFUNCTIONING PART 

    Check the following.

  10. CHECK IGNITION TIMING 

    Check the following items. Refer to BASIC INSPECTION .

    CHECK IGNITION TIMING REFERENCE DATA

    Items Specifications
    Target idle speed 650 +/- 50 RPM (in P or N position)
    Ignition timing 15 +/- 5° BTDC (in P or N position)

    OK or NG

    OK: GO TO 11.

    NG: Follow the BASIC INSPECTION .

  11. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect A/F sensor 1 harness connector.
      Fig 6: Locating A/F Sensor 1
      G02691369Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between the following terminals.

      Refer to WIRING DIAGRAM .

      Fig 7: ECM Terminals & A/F Sensor 1 Terminals Harness Continuity Table (Continuity Should Exist)
      G02691370Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    5. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
      CHECKING HARNESS CONTINUITY TERMINALS

      Bank 1 Bank 2
      A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
      1 16 1 76
      2 75 2 77
      5 35 5 57
      6 56 6 58

      Continuity should not exist. 

    6. Also check harness for short to power.

    OK or NG

    OK: GO TO 12.

    NG: Repair open circuit or short to ground or short to power in harness or connectors between ECM and A/F sensor 1.

  12. CHECK A/F SENSOR 1 HEATER (BANK 1)/(BANK 2) 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 13.

    NG: Replace (malfunctioning) A/F sensor 1.

  13. CHECK MASS AIR FLOW SENSOR 

    WITH CONSULT-II 

    Check mass air flow sensor signal in "DATA MONITOR" mode with CONSULT-II.

    3.0 - 9.0 g.m/sec: at idling 

    9.0 - 28.0 g.m/sec: at 2,500 RPM 

    WITH GST 

    Check mass air flow sensor signal in MODE 1 with GST.

    3.0 - 9.0 g.m/sec: at idling 

    9.0 - 28.0 g.m/sec: at 2,500 RPM 

    OK or NG

    OK: GO TO 14.

    NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds. Refer to DTC P0101 MAF SENSOR .

  14. CHECK SYMPTOM MATRIX CHART 

    Check items on the rough idle symptom in SYMPTOM MATRIX CHART .

    OK or NG

    OK: GO TO 15.

    NG: Repair or replace.

  15. ERASE THE 1ST TRIP DTC 

    Some tests may cause a 1st trip DTC to be set.

    Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION .

    : GO TO 16.

  16. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    : INSPECTION END 

scientia non olet · About LEMON Manuals