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Home >> Nissan-Datsun >> 2006 >> Maxima SL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0138 To P0445 >> 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 (manifold).
      Fig 1: Inspecting For Exhaust Gas Leaks
      G04191081Courtesy 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: Locating A/F Sensor 1 (Banks 1 And 2) Harness Connector
      G04160220Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between the following terminals.

      Refer to WIRING DIAGRAM .

      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 .

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

    OK or NG 

    OK (With CONSULT-II): GO TO  6.

    OK (Without CONSULT-II): GO TO  7.

    NG: GO TO  5.

  5. DETECT MALFUNCTIONING PART 

    Check the following.

  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 

    OK or NG 

    OK: 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 MASS AIR FLOW SENSOR 

    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 (P0171): GO TO  9.

    OK (P0174): GO TO  11.

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

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

    OK or NG 

    OK: GO TO  12.

    NG: Perform trouble diagnosis for "FUEL INJECTOR ".

  9. CHECK FUNCTION OF FUEL INJECTOR-I 

    Without CONSULT-II 

    1. Stop engine.
    2. Disconnect harness connector F44 (1), F101 (2).
      • <=: Vehicle front
      • Intake manifold collector (3)
    3. Turn ignition switch ON.
      Fig 4: Disconnecting Harness Connector F44, F101
      G04160409Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check voltage between harness connector F44 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 harness connector F44 and ECM as follows.
      Fig 5: Checking Voltabe Between Harness Connector Terminal 5 And Ground
      G04073991Courtesy of NISSAN MOTOR CO., U.S.A.

      Refer to WIRING DIAGRAM .

      CONTINUITY REFERENCE

      Cylinder Harness connector F44 terminal ECM terminal
      1 6 23
      3 2 22
      5 1 21

      Continuity should exist  .

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

    OK or NG 

    OK: GO TO  10.

    NG: Perform trouble diagnosis for "FUEL INJECTOR ".

  10. CHECK FUNCTION OF FUEL INJECTOR-II 

    Provide battery voltage between harness connector F101 as follows and then interrupt it. Listen to each fuel injector operating sound.

    Fig 6: Providing Battery Voltage Between Harness Connector F101
    G04160411Courtesy of NISSAN MOTOR CO., U.S.A.
    VOLTAGE REFERENCE

    Cylinder Harness connector F101 terminal
    (+) (-)
    1 5 6
    3 5 2
    5 5 1

    Operating sound should exist  .

    OK or NG 

    OK: GO TO  12.

    NG: Perform trouble diagnosis for "FUEL INJECTOR ".

  11. CHECK FUNCTION OF FUEL INJECTOR 
    1. Start engine.
    2. Listen to fuel injectors No. 2, No. 4, No. 6 operating sound.

      Clicking noise should exist  .

      3. Fig 7: Checking Fuel Injector For Audible Clicking
      G04132840Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  12.

    NG: Perform trouble diagnosis for "FUEL INJECTOR ".

  12. 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. Disconnect all fuel injector harness connectors.
    4. Remove fuel injector gallery assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ".

      Keep fuel hose and all fuel injectors connected to fuel injector gallery.

    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  .

      9. Fig 8: Checking Fuel Injector Spray
      G04160413Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO  13.

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

  13. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    : INSPECTION END 

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