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Home >> Infiniti >> 2008 >> FX35 RWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P0137 Through P0445 (VQ35DE) >> 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 Leakage
    G04875054Courtesy 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 AIR FUEL RATIO (A/F) SENSOR 1 INPUT SIGNAL CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect corresponding air fuel ration (A/F) sensor 1 harness connector.
      Fig 2: Identifying A/F Sensor Harness Connector (Bank 1/Bank 2)
      G05216324Courtesy 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 AND ECM TERMINALS REFERENCE

        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 AND ECM TERMINALS REFERENCE

      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 ground and 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.

  6. CHECK MASS AIR FLOW SENSOR 

    With CONSULT-III 

    1. Install all removed parts.
    2. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-III.

      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-III)>>GO TO  7.

    OK (Without CONSULT-III)>>GO TO  8.

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

  7. CHECK FUNCTION OF FUEL INJECTOR 

    With CONSULT-III 

    1. Start engine.
    2. Perform "POWER BALANCE" in "ACTIVE TEST " mode with CONSULT-III.
    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 ".

  8. CHECK FUNCTION OF FUEL INJECTOR-I 

    Without CONSULT-III 

    1. Turn ignition switch OFF.
    2. Disconnect harness connectors F50, F251
    3. Turn ignition switch ON.
      Fig 3: Identifying Camshaft Position Sensor And Intake Manifold Collector
      G05216515Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between harness connector F50 terminal 5 and ground with CONSULT-III or tester.

      Voltage: Battery voltage 

    5. Turn ignition switch OFF.
    6. Disconnect ECM harness connector.
    7. Check harness continuity between harness connector F50 and ECM as follows.

      Refer to WIRING DIAGRAM .

      Fig 4: Checking Voltage Between Fuel Injector Connector F50 Terminal 5 And Ground
      G04905407Courtesy of NISSAN MOTOR CO., U.S.A.
      CYLINDER AND ECM TERMINALS REFERENCE

      Cylinder Harness connector F50 terminal ECM terminal
      1 6 23
      2 4 42
      3 2 22
      4 3 41
      5 1 21
      6 7 40

      Continuity should exist. 

    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 

    Provide battery voltage between harness connector F251 as follows and then interrupt it. Listen to each fuel injector operating sound.

    Fig 5: Applying Battery Voltage Between Fuel Injector Connector Terminals
    G05216517Courtesy of NISSAN MOTOR CO., U.S.A.
    CYLINDER AND FUEL INJECTOR TERMINALS REFERENCE

    Cylinder Harness connector F251 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. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
    2. Turn ignition switch OFF.
    3. Reconnect all harness connectors disconnected.
    4. Disconnect all fuel injector harness connectors.
    5. Remove fuel injector gallery assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ". Keep fuel hose and all fuel injectors connected to fuel injector gallery.
    6. For DTC P0171, reconnect fuel injector harness connectors on bank 1. For DTC P0174, reconnect fuel injector harness connectors on bank 2.
    7. Disconnect all ignition coil harness connectors.
    8. Prepare pans or saucers under each fuel injector.
    9. 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. 

    Fig 6: Checking Fuel Injector
    G04875113Courtesy of NISSAN MOTOR CO., U.S.A.

    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.

  11. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT "

    >> INSPECTION END 

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