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Home >> Infiniti >> 2008 >> G35 Base >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P0137 Through P0430 >> DTC P0420, P0430: Three Way Catalyst Function >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK EXHAUST SYSTEM

    Visually check exhaust tubes and muffler for dent.

    Is the inspection result normal? 

    YES: GO TO 2.

    NO: Repair or replace.

  2. CHECK EXHAUST GAS LEAK
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before the three way catalyst 1.
      Fig 1: Inspecting Exhaust Gas Leak
      G04875054Courtesy of NISSAN MOTOR CO., U.S.A.

    Is exhaust gas leak detected? 

    YES: Repair or replace.

    NO: GO TO 3.

  3. CHECK INTAKE AIR LEAK

    Listen for an intake air leak after the mass air flow sensor.

    Is intake air leak detected? 

    YES: Repair or replace.

    NO: GO TO 4.

  4. CHECK IGNITION TIMING

    Check the following items. Refer to "BASIC INSPECTION : SPECIAL REPAIR REQUIREMENT ".

    ITEM SPECIFICATION

    Items Specifications
    Target idle speed A/T: 650 ± 50 rpm (in P or N position)
    M/T: 650 ± 50 rpm (in Neutral position)
    Ignition timing A/T with 4WAS: 11 ± 5° BTDC (in P or N position)
    A/T without 4WAS: 15 ± 5° BTDC (in P or N position)
    M/T with 4WAS: 11 ± 5° BTDC (in Neutral position)
    M/T without 4WAS: 15 ± 5° BTDC (in Neutral position)

    Is the inspection result normal? 

    YES: GO TO 5.

    NO: Follow the "BASIC INSPECTION : SPECIAL REPAIR REQUIREMENT ".

  5. CHECK FUEL INJECTORS
    1. Stop engine and then turn ignition switch ON.
    2. Check the voltage between ECM harness connector and ground.
      TERMINALS VOLTAGE REFERENCE

      ECM Ground Voltage
      Connector Terminal
      F102 81 Ground Battery voltage
      82
      85
      86
      89
      90

    Is the inspection result normal? 

    YES: GO TO 6.

    NO: Perform "DIAGNOSIS PROCEDURE ".

  6. CHECK FUNCTION OF IGNITION COIL-I
    CAUTION: Do the following procedure in the place where ventilation is good without the combustible.
    1. Turn ignition switch OFF.
    2. Remove fuel pump fuse (1) in IPDM E/R (2) to release fuel pressure.
      NOTE: Do not use CONSULT-III to release fuel pressure, or fuel pressure applies again during the following procedure.
    3. Start engine.
    4. After engine stalls, crank it two or three 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.
      Fig 2: Identifying Fuel Pump Fuse In IPDM E/R
      G05207189Courtesy of NISSAN MOTOR CO., U.S.A.
    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.
    11. Crank engine for about 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.
      Fig 3: Checking For Spark
      G04886523Courtesy of NISSAN MOTOR CO., U.S.A.

      Spark should be generated. 

      CAUTION:
      • Do not approach to the spark plug and the ignition coil within 50 cm (19.7 in). Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20kV or more.
      • It might cause to damage the ignition coil if the gap of more than 17 mm (0.66 in) is taken.
      NOTE: When the gap is less than 13 mm (0.52 in), the 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 known-good spark plug.
    3. Crank engine for about 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.

    Is the inspection result normal? 

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

    NO: Repair or clean spark plug. Then GO TO 9.

    Fig 4: Checking Initial Spark Plug For Fouling
    G04875165Courtesy of NISSAN MOTOR CO., U.S.A.
  9. CHECK FUNCTION OF IGNITION COIL-III
    1. Reconnect the initial spark plugs.
    2. Crank engine for about three 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 ".

  10. CHECK FUEL INJECTOR
    1. Turn ignition switch OFF.
    2. Remove fuel injector assembly.

      Refer to "REMOVAL AND INSTALLATION ".

      Keep fuel hose and all fuel injectors connected to fuel tube.

    3. Disconnect all ignition coil harness connectors.
    4. Reconnect all fuel injector harness connectors disconnected.
    5. Turn ignition switch ON.

    Does fuel drip from fuel injector? 

    YES: Replace the fuel injector(s) from which fuel is dripping.

    NO: GO TO 11.

  11. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    Is the trouble fixed? 

    YES: INSPECTION END

    NO: Replace three way catalyst assembly.

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