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Home >> Nissan-Datsun >> 2004 >> Sentra SE-R >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Qr25DE >> DTC P0171: Fuel Injection System Function >> Diagnostic Procedure >> A/T Models ULEV And M/T Models
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A/T Models ULEV And M/T Models

  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: Checking Exhaust Gas Leak
      G00777088Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 2.
    2. NG: Repair or replace.
  2. CHECK FOR INTAKE AIR LEAK AND PCV HOSE 
    1. Listen for an intake air leak after the mass air flow sensor.
    2. Check PCV hose connection.

    OK or NG 

    1. OK: GO TO 3.
    2. NG: Repair or replace.
  3. CHECK HEATED OXYGEN SENSOR 1 CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect heated oxygen sensor 1 (HO2S1) harness connector.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between ECM terminal 35 and HO2S1 terminal 1.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    5. Check harness continuity between ECM terminal 35 or HO2S1 terminal 1 and ground. Refer to WIRING DIAGRAM .

      Continuity should not exist. 

    6. Also check harness for short to power.
    7. Fig 2: Disconnecting HO2S1 Harness Connector
      G00777089Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 4.
    2. 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 

    1. OK: GO TO 5.
    2. NG: Follow the instruction of FUEL PRESSURE CHECK.
  5. 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.

      1.4 - 4.0 g.m/sec: at idling 

      4.0 - 10 g.m/sec: at 2, 500 RPM 

    With GST 

    1. Install all removed parts.
    2. Check mass air flow sensor signal in MODE 1 with GST.

      1.4 - 4.0 g.m/sec: at idling 

      4.0 -10 g.m/sec: at 2, 500 RPM 

    OK or NG 

    1. OK: GO TO 6.
    2. NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds. Refer to "DTC P0101 MAF SENSOR ".
  6. CHECK FUNCTION OF INJECTORS 

    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: Identifying Active Test Mode Of Consult-II
      G00777090Courtesy of NISSAN MOTOR CO., U.S.A.

    Without CONSULT-II 

    1. Start engine.
    2. Listen to each injector operating sound.

      Clicking noise should be heard. 

      Fig 4: Checking Function Of Injectors (Without CONSULT-II)
      G00777091Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 7.
    2. NG: perform trouble diagnosis for "INJECTOR CIRCUIT ".
  7. CHECK 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 injector harness connectors.
    4. Remove injector gallery assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ". Keep fuel hose and all injectors connected to injector gallery.

      The injector harness connectors should remain connected.

    5. Disconnect all ignition coil harness connectors.
    6. Prepare pans or saucers under each injector.
    7. Crank engine for about 3 seconds. Make sure that fuel sprays out from injectors.

      Fuel should be sprayed evenly for each injector. 

    8. Fig 5: Checking Injector
      G00777092Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 8.
    2. NG: Replace injectors from which fuel does not spray out. Always replace O-ring with new ones.
  8. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. INSPECTION END