Diagnostic Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
   Fig 1: Checking Exhaust Manifold For Gas Leak

   Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG 

1. OK GO TO 2.
2. NG Repair or replace.

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.

1. Turn ignition switch "OFF".
2. Disconnect corresponding heated oxygen sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between ECM terminal and HO2S1 terminal as follows.

   Refer to WIRING DIAGRAM  .

   Fig 2: ECM Terminal And HO2S1 Terminals Table (For Continuity Checking)

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Continuity should exist. 

5. Check harness continuity between ECM terminal or HO2S1 terminal and ground as follows.

   Refer to WIRING DIAGRAM  .

   Fig 3: ECM Terminal Or HO2S1 Terminal And Ground Table (For Continuity Checking)

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Continuity should not exist. 

6. Also check harness for short to power.

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.

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: 

   When fuel pressure regulator valve vacuum hose is connected. 

   235 kPa (2.4 kg/cm ² , 34 psi) 

   When fuel pressure regulator valve vacuum hose is disconnected. 

   294 kPa (3.0 kg/cm ² , 43 psi) 

OK or NG 

1. OK GO TO  6 .
2. NG GO TO 5.

Check the following.

• Fuel pump and circuit (Refer to FUEL PUMP  .)
• Fuel pressure regulator (Refer to Fuel Pressure Regulator Check  .)
• Fuel lines .)
• Fuel filter for clogging

1. Repair or replace.

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 

With GST 

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

1. OK GO TO 7.
2. NG Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds. Refer to DTC P0102, P0103 MAF SENSOR  .

With CONSULT-II 

1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-II.
   Fig 4: Display CONSULT II (Active Test)

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Make sure that each circuit produces a momentary engine speed drop.

Without CONSULT-II 

1. Start engine.
2. Listen to each injector operating sound.
   Fig 5: Checking Injector Operating Sound

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Clicking noise should be heard. 

OK or NG 

1. OK GO TO 8.
2. NG Perform trouble diagnosis for "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 REMOVAL AND INSTALLATION  .

   Keep fuel hose and all injectors connected to injector gallery.

5. For DTC P0171, reconnect injector harness connectors on bank 1.

   For DTC P0174, reconnect injector harness connectors on bank 2.

6. Disconnect all ignition coil harness connectors.
7. Prepare pans or saucers under each injector.
8. Crank engine for about 3 seconds.

   For DTC P0171, make sure that fuel sprays out from injectors on bank 1.

   For DTC P0174, make sure that fuel sprays out from injectors on bank 2.

   Fig 6: Checking Injector

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Fuel should be sprayed evenly for each injector. 

OK or NG 

1. OK GO TO 9.
2. NG Replace injectors from which fuel does not spray out. Always replace O-ring with new ones.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  " .

1. INSPECTION END