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Home >> Infiniti >> 2021 >> QX80 Luxe, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (2 Of 5) >> Engine (ECM) >> DTC P0300: Misfire >> DTC Diagnosis Procedure

DTC Diagnosis Procedure

  1. CHECK GROUND CONNECTION 

    Check the following.

    • Connection condition of the ground F33 and F34.
    • Connection condition of the ground harness between engine assembly and vehicle body (If equipped).

    Is the inspection result normal?

    YES

    GO TO 2.

    NO

    Repair or replace error-detected parts.

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

    Is intake air leakage detected?

    YES

    Discover air leakage location and repair.

    NO

    GO TO 3.

  3. CHECK FOR EXHAUST SYSTEM CLOGGING 

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

    Is the inspection result normal?

    YES

    With CONSULT: GO TO 4.

    YES

    Without CONSULT: GO TO 5.

    NO

    Repair or replace malfunctioning part.

  4. PERFORM POWER BALANCE TEST 

    SYMBOL WITH CONSULT

    1. Start engine.
    2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT.
    3. Check that each circuit produces a momentary engine speed drop.

    Is the inspection result normal?

    YES

    GO TO 10.

    NO

    GO TO 5.

  5. CHECK FUNCTION OF FUEL INJECTOR-I 
    1. Start engine and let it idle.
    2. Listen to each fuel injector operation.
      G04812223Courtesy of NISSAN NORTH AMERICA, INC.

      Clicking sound should be heard.

    Is the inspection result normal?

    YES

    GO TO 6.

    NO

    Perform trouble diagnosis for FUEL INJECTOR, refer to Diagnosis Procedure .

  6. CHECK FUNCTION OF IGNITION COIL-I 
    CAUTION: Perform the following procedure in a place with no combustible objects and good ventilation.
    1. Turn ignition switch OFF.
    2. Remove fuel pump fuse No. in IPDM E/R to release fuel pressure.
      NOTE: Do not use CONSULT to release fuel pressure, or fuel pressure applies again during the following procedure.
    3. Start engine.
    4. After engine stalls, crank it 2 or 3 times to release all fuel pressure.
    5. Turn ignition switch OFF.
    6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
    7. Remove ignition coil and spark plug of the cylinder to be checked.
    8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
    9. Connect spark plug and harness connector to ignition coil.
    10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm (0.52 - 0.66 in) between the edge of the spark plug and grounded metal portion as shown in the figure.
      G04886523Courtesy of NISSAN NORTH AMERICA, INC.
    11. Crank engine for approximately 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

      Spark should be generated.
      CAUTION:
      • Never place the spark plug and the ignition coil within 50 cm (19.7 in) each other. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
      • It might damage the ignition coil if the gap of more than 17 mm (0.66 in) is made.
      NOTE: When the gap is less than 13 mm (0.52 in), a spark might be generated even if the coil is malfunctioning.

    Is the inspection result normal?

    YES

    GO TO 10.

    NO

    GO TO 7.

  7. CHECK FUNCTION OF IGNITION COIL-II 
    1. Turn ignition switch OFF.
    2. Disconnect spark plug and connect a non-malfunctioning spark plug.
    3. Crank engine for approximately 3 seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.

      Spark should be generated.

    Is the inspection result normal?

    YES

    GO TO 8.

    NO

    Check ignition coil, power transistor and their circuits. Refer to Diagnosis Procedure .

  8. CHECK SPARK PLUG 

    Check the initial spark plug for fouling, etc.

    G04185314Courtesy of NISSAN NORTH AMERICA, INC.

    Is the inspection result normal?

    YES

    Replace spark plug(s) with standard type one(s). For spark plug typ, refer to SPARK PLUG : Service Data .

    NO

    Repair or clean spark plug. Then GO TO 9.

  9. CHECK FUNCTION OF IGNITION COIL-III 
    1. Reconnect the initial spark plugs.
    2. Crank engine for approximately 3 seconds, and recheck whether spark is generated between the spark plug and the grounded portion.

      Spark should be generated.

    Is the inspection result normal?

    YES

    INSPECTION END

    NO

    Replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG : Service Data .

  10. CHECK COMPRESSION PRESSURE 

    Check compression pressure. Refer to Inspection .

    Is the inspection result normal?

    YES

    GO TO 11.

    NO

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

  11. CHECK FUEL PRESSURE 
    1. Install all removed parts.
    2. Check fuel pressure. Refer to Work Procedure .

    Is the inspection result normal?

    YES

    GO TO 13.

    NO

    GO TO 12.

  12. DETECT MALFUNCTIONING PART 

    Check fuel hoses and fuel tubes for clogging.

    Is the inspection result normal?

    YES

    Replace "fuel filter and fuel pump assembly".

    NO

    Repair or replace malfunctioning part.

  13. CHECK IDLE SPEED AND IGNITION TIMING 

    Check idle speed and ignition timing.

    For procedure, refer to IDLE SPEED : Periodic Maintenance Operation . And Refer to IGNITION TIMING : Periodic Maintenance Operation . Refer to IGNITION TIMING : Periodic Maintenance Operation .

    For specification, refer to IDLE SPEED : Service Data . and Refer to IGNITION TIMING : Service Data .

    Is the inspection result normal?

    YES

    GO TO 14.

    NO

    Follow the Work Procedure .

  14. CHECK AIR FUEL RATIO SENSOR 1 POWER SUPPLY 
    1. Turn ignition switch OFF.
    2. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between A/F sensor 1 harness connector and ground.

      DTC

      A/F sensor 1

      Ground

      Voltage

      Bank

      Connector

      Terminal

      P0130

      1

      F133

      4

      Ground

      Battery voltage

      P0150

      2

      F134

      4

    Is the inspection result normal?

    YES

    GO TO 16.

    NO

    GO TO 15.

  15. CHECK AIR FUEL RATIO SENSOR 1 POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between A/F sensor 1 harness connector and IPDM E/R harness connector.

      DTC

      A/F sensor 1

      IPDM E/R

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      P0130

      1

      F133

      4

      E14

      35

      Existed

      P0150

      2

      F134

      4
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES

    Perform trouble diagnosis for power supply circuit.

    NO

    Repair or replace malfunctioning part.

  16. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

      Bank

      A/F sensor 1

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      1

      F133

      1

      F92

      79

      Existed

      2

      74

      2

      F134

      1

      F92

      69

      2

      70
    4. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

      Bank

      A/F sensor 1

      Ground

      Continuity

      Connector

      Terminal

      1

      F133

      1

      Ground

      Not Existed

      2

      2

      F134

      1

      2

      Bank

      ECM

      Ground

      Continuity

      Connector

      Terminal

      1

      F92

      79

      Ground

      Not Existed

      74

      2

      F92

      69

      70
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES

    GO TO 17.

    NO

    Repair or replace malfunctioning part.

  17. CHECK A/F SENSOR 1 HEATER 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 18.

    NO

    Replace malfunctioning A/F sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST : Exploded View .

  18. CHECK MASS AIR FLOW SENSOR 

    SYMBOL WITH CONSULT

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

    For specification, refer to Component Inspection .

    SYMBOL WITH GST

    Check mass air flow sensor signal in Service $01 with GST.

    For specification, refer to Component Inspection .

    Is the measurement value within the specification?

    YES

    GO TO 19.

    NO

    Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to DTC Diagnosis Procedure .

  19. CHECK SYMPTOM MATRIX CHART 

    Check items on the rough idle symptom in Refer to Symptom Table .

    Is the inspection result normal?

    YES

    GO TO 20.

    NO

    Repair or replace malfunctioning part.

  20. 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. SYMBOL or Refer to Diagnosis Description . SYMBOL Refer to Diagnosis Description .

    GO TO 21.

  21. CHECK INTERMITTENT INCIDENT 

    Refer to Inspection .

    INSPECTION END

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