Toyota
Nissan Versa
 Sedan Service Manual
Engine » Engine control system (EC) » P0171 fuel injection system function
Diagnosis 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).

CHECK EXHAUST GAS LEAK

Is exhaust gas leak detected?

YES >> Repair or replace.

NO >> GO TO 2.

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.

Intake air leak detected?

YES >> Repair or replace.

NO >> GO TO 3.

3.CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

  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.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

    5.   Check the continuity between A/F sensor 1 harness connector or ECM harness connector and ground.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

    6.   Also check harness for short to power.

Is the inspection result normal?

YES >> GO TO 4.

NO >> 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 EC, "Work Procedure".
  2. Install fuel pressure gauge and check fuel pressure. Refer to EC, "Work Procedure".

At idling: Approximately 350 kPa (3.57 kg/cm2, 51 psi)

Is the inspection result normal?

YES >> GO TO 6.

NO >> GO TO 5.

5. CHECK FUEL HOSES AND FUEL TUBES

Check fuel hoses and fuel tubes for clogging.

Is the inspection result normal?

YES >> Replace "fuel filter and fuel pump assembly". Refer to FL, "Exploded View".

NO >> Repair or replace

6.CHECK MASS AIR FLOW SENSOR

With CONSULT

  1. Install all removed parts.
  2. Check "MASS AIRFLOW" in "DATA MONITOR" mode with CONSULT.

0.8 4.0 g/s : at idling

2.0 10.0 g/s : at 2,500 rpm

With GST

  1. Install all removed parts.
  2. Check mass air flow sensor signal in Service $01 with GST.

0.8 4.0 g/s : at idling

2.0 10.0 g/s : at 2,500 rpm

Is the measurement value within the specification?

YES >> GO TO 7.

NO >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to EC, "DTC Logic".

7.CHECK FUNCTION OF FUEL INJECTOR

With CONSULT

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

Without CONSULT

  1. Let engine idle.
  2. Listen to each fuel injector operating sound.

Clicking noise should be heard.

Is the inspection result normal?

YES >> GO TO 8.

NO >> Perform trouble diagnosis for FUEL INJECTOR. Refer to EC, "Component Function Check".

CHECK FUNCTION OF FUEL INJECTOR

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 EM, "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.

Fuel should be sprayed evenly for each fuel injector.

Is the inspection result normal?

YES >> GO TO 9.

NO >> Replace fuel injectors from which fuel does not spray out. Always replace Oring with new ones. Refer to EM, "Removal and Installation".

CHECK FUEL INJECTOR

9.  CHECK INTERMITTENT INCIDENT

Refer to GI, "Intermittent Incident".

>> INSPECTION END

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