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Home >> Nissan-Datsun >> 2016 >> Sentra FE+S >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (DTCS) (1 Of 3) >> DTC/Circuit Diagnosis >> DTC P0171: Fuel Injection System Function >> Diagnosis Procedure >> Diagnostic Test
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Diagnostic Test

  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
      G04191081Courtesy of NISSAN NORTH AMERICA, INC.

    Is exhaust gas leak detected?

    YES 

    Repair or replace error-detected parts.

    NO 

    GO TO STEP 2  .

  2. CHECK FOR INTAKE AIR LEAK

    1. Listen for an intake air leak after the mass air flow sensor.
    2. Check PCV hose connection.

    Intake air leak detected?

    YES 

    Repair or replace error-detected parts.

    NO 

    GO TO STEP 3  .

  3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT

    1. Turn ignition switch OFF.
    2. Disconnect corresponding A/F sensor 1 harness connector.
    3. Disconnect ECM harness connector.
    4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
      + - Continuity
      A/F sensor 1 ECM
      Connector Terminal Connector Terminal
      F12* 1
      F42* 2      		 1 F24 41 Existed
      2 45

      *1: Except California

      *2: For California

    5. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.
      + - Continuity
      A/F sensor 1
      Connector Terminal
      F12* 1
      F42* 2      		 1 Ground Not existed
      2

      *1: Except California

      *2: For California

      + - Continuity
      ECM
      Connector Terminal
      F24 41 Ground Not existed
      45
    6. Also check harness for short to power.

    Is the inspection result normal?

    YES 

    GO TO STEP 4  .

    NO 

    Repair or replace error-detected parts.

  4. CHECK FUEL PRESSURE

    Check fuel pressure. Refer to WORK PROCEDURE .

    Is the inspection result normal?

    YES 

    GO TO STEP 6  .

    NO 

    GO TO STEP 5  .

  5. DETECT MALFUNCTIONING PART

    Check fuel hoses and fuel tubes for clogging. Refer to EXPLODED VIEW .

    Is the inspection result normal?

    YES 

    Replace "fuel filter and fuel pump assembly". Refer to REMOVAL AND INSTALLATION .

    NO 

    Repair or replace error-detected parts.

  6. CHECK MASS AIR FLOW SENSOR

    G-20 With CONSULT

    1. Turn ignition switch OFF.
    2. Reconnect all harness connectors disconnected.
    3. Start engine and warm it up to normal operating temperature.
    4. Connect CONSULT and select "DATA MONITOR" mode.
    5. Select "MASS AIR FLOW SENSOR (Hz)" and check the indication.
      Monitor item Condition Indication (Hz)
      MASS AIR FLOW SENSOR (Hz) Ignition switch ON (Engine stopped.) Approx. 3, 700 Hz
      Idle (Engine is warmed-up to normal operating temperature.) 5, 100 - 5, 500 Hz
      Idle to about 4, 000 RPM 5, 100 - 5, 500 to Approx. 7, 000 Hz*

      *: Check for linear frequency rise in response to engine being increased to about 4, 000 RPM.

    G-21 Without CONSULT

    1. Turn ignition switch OFF.
    2. Reconnect all harness connectors disconnected.
    3. Start engine and warm it up to normal operating temperature.
    4. Check the frequency between ECM harness connector terminals under the following conditions.
      ECM Condition Frequency (Hz)
      Connector + -
      Terminal
      F24 35 34 Ignition switch ON (Engine stopped.) Approx. 3, 700 Hz
      Idle (Engine is warmed-up to normal operating temperature.) 5, 100 - 5, 500 Hz
      Idle to about 4, 000 RPM 5, 100 - 5, 500 to Approx. 7, 000 Hz*

      * : Check for linear frequency rise in response to engine being increased to about 4, 000 RPM.

    Is the inspection result normal?

    YES 

    GO TO STEP 7  .

    NO 

    Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to DTC LOGIC .

  7. CHECK FUNCTION OF FUEL INJECTOR

    G-20 With CONSULT

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

    G-21 Without CONSULT

    1. Let engine idle.
    2. Listen to each fuel injector operating sound.
      Fig 2: Checking Fuel Injector Operating Sound
      G04812223Courtesy of NISSAN NORTH AMERICA, INC.
      Clicking noise should be heard.

    Is the inspection result normal?

    YES 

    GO TO STEP 8  .

    NO 

    Perform trouble diagnosis for "FUEL INJECTOR". Refer to COMPONENT FUNCTION CHECK .

  8. 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 REMOVAL AND INSTALLATION .

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

    5. Disconnect all ignition coil harness connectors.
    6. Prepare pans or saucers under each fuel injector.
    7. Crank engine for about 3 seconds.
      Fig 3: Checking Fuel Injector Spray
      G04812224Courtesy of NISSAN NORTH AMERICA, INC.
      Fuel should be sprayed evenly for each fuel injector.

    Is the inspection result normal?

    YES 

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    NO 

    Replace fuel injectors from which fuel does not spray out. Always replace O-ring with new ones. Refer to REMOVAL AND INSTALLATION .

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