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Home >> Infiniti >> 2006 >> M35 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (VQ35DE) - DTCS P0137 To P0448 >> DTC P0171, P0174 Fuel Injection System Function >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK EXHAUST GAS LEAK 
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before three way catalyst 1.
    Fig 1: Checking Exhaust Gas Leak
    G04138504Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  2.

    NG: Repair or replace.

  2. CHECK FOR INTAKE AIR LEAK 
    1. Listen for an intake air leak after the mass air flow sensor.
    2. Check PCV hose connection.

    OK or NG 

    OK: GO TO  3.

    NG: Repair or replace.

  3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect corresponding A/F sensor 1 harness connector.
      Fig 2: Identifying A/F Sensor 1 Harness Connector
      G04138505Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between the following terminals.

      Refer to Wiring Diagram .

      A/F SENSOR 1 TERMINAL AND ECM TERMINAL

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

      Continuity should exist. 

    5. Check harness continuity between the following terminals and ground.

      Refer to Wiring Diagram .

      A/F SENSOR 1 TERMINAL AND ECM TERMINAL AND GROUND

      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  4.

    NG: Repair open circuit or short to ground or short to power in harness or connectors.

  4. CHECK FUEL PRESSURE 
    1. Release fuel pressure to zero. Refer to , "FUEL PRESSURE RELEASE ".
    2. Install fuel pressure gauge and check fuel pressure. Refer to , "FUEL PRESSURE CHECK ".

    At idling: Approximately 350 kPa (3.57 kg/cm 2  , 51 psi) 

    OK or NG 

    OK: GO TO  6.

    NG: GO TO  5.

  5. DETECT MALFUNCTIONING PART 

    Check the following.

    Repair or replace.

  6. CHECK MASS AIR FLOW SENSOR 

    With CONSULT-II 

    1. Install all removed parts.
    2. Check "MASS AIR FLOW" in "DATA MONITOR" 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 

    1. Install all removed parts.
    2. Check mass air flow sensor signal in Service $01 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 (With CONSULT-II): GO TO  7.

    OK (Without CONSULT-II): GO TO  8.

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

  7. CHECK FUNCTION OF FUEL INJECTOR 

    With CONSULT-II 

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

    OK or NG 

    OK: GO TO  10.

    NG: Perform trouble diagnosis for FUEL INJECTOR, refer to , "FUEL INJECTOR ".

    Fig 3: Consult-II ACTIVE TEST Display Screen
    G04080452Courtesy of NISSAN MOTOR CO., U.S.A.
  8. CHECK FUNCTION OF FUEL INJECTOR-I 

    Without CONSULT-II 

    1. Turn ignition switch OFF.
    2. Disconnect harness connectors F221 (1), F33 (2).
      • : vehicle front
      • Cylinder head (bank 2) (3)
    3. Turn ignition switch ON.
      Fig 4: Identifying Harness Connectors F221 (1), F33 (2)
      G04138507Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between harness connector F33 terminal 5 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    5. Turn ignition switch OFF.
    6. Disconnect ECM harness connector.
    7. Check harness continuity between the following terminals.
      CYLINDER HARNESS CONNECTOR F33 TERMINAL AND ECM TERMINAL

      Cylinder Harness connector F33 terminal ECM terminal
      1 6 23
      2 4 42
      3 2 22
      4 3 41
      5 1 21
      6 7 40

      Continuity should exist. 

      Fig 5: Checking Voltage Between Harness Connector Terminal 5 And Ground
      G04073991Courtesy of NISSAN MOTOR CO., U.S.A.
    8. Also check harness for short to ground and short to power.

    OK or NG 

    OK: GO TO  9.

    NG: Perform trouble diagnosis for FUEL INJECTOR, refer to , "FUEL INJECTOR ".

  9. CHECK FUNCTION OF FUEL INJECTOR-II 
    Fig 6: Checking Function Of Fuel Injector-II
    G04138509Courtesy of NISSAN MOTOR CO., U.S.A.

    Provide battery voltage between the following terminals, and then interrupt it. Listen to each fuel injector operating sound.

    CYLINDER HARNESS AND CONNECTOR F221 TERMINAL

    Cylinder Harness connector F221 terminal
    (+) (-)
    1 5 6
    2 4
    3 2
    4 3
    5 1
    6 7

    Operating sound should exist. 

    OK or NG 

    OK: GO TO  10.

    NG: Perform trouble diagnosis for FUEL INJECTOR, refer to , "FUEL INJECTOR ".

  10. CHECK FUEL INJECTOR 
    1. Turn ignition switch OFF.
    2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
    3. Disconnect all fuel injector harness connectors.
    4. Remove fuel tube assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ".

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

    5. For DTC P0171, reconnect fuel injector harness connectors on bank 1.

      For DTC P0174, reconnect fuel injector harness connectors on bank 2.

    6. Disconnect all ignition coil harness connectors.
    7. Prepare pans or saucers under each fuel injector.
    8. Crank engine for about 3 seconds.

      For DTC P0171, make sure that fuel sprays out from fuel injectors on bank 1.

      For DTC P0174, make sure that fuel sprays out from fuel injectors on bank 2.

      Fuel should be sprayed evenly for each fuel injector. 

    OK or NG 

    OK: GO TO  11.

    NG: Replace fuel injectors from which fuel does not spray out. Always replace O-ring with new ones.

    Fig 7: Checking Working Of Fuel Injector-II
    G04138510Courtesy of NISSAN MOTOR CO., U.S.A.
  11. CHECK INTERMITTENT INCIDENT 

    Refer to , "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    INSPECTION END 

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