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 Gas Leak

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

OK or NG 

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

Listen for an intake air leak after the mass air flow sensor.

OK or NG 

1. OK: GO TO 3.
2. NG: Repair or replace.

Check PCV hose for loose connection or disconnection.

OK or NG 

1. OK: GO TO 4.
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: Identifying Circuit Between ECM Terminal And HO2S1 Terminal

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

   Continuity should exist. 

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

   Refer to WIRING DIAGRAM .

   Fig 3: Identifying Circuit Between ECM Terminal And Ground

   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 5.
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  7.
2. NG: GO TO 6.

Check the following.

• Fuel pump and circuit (Refer to FUEL PUMP CIRCUIT ).
• Fuel pressure regulator (Refer to FUEL PRESSURE CHECK (+)
• Fuel lines (Refer to "CHECKING FUEL LINES )".
• Fuel filter for clogging

: Repair or replace.

With CONSULT-II 

1. Install all parts removed.
2. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-II.

   3.3 - 4.8 g.m/sec: at idling 

   12.0 - 14.9 g.m/sec: at 2, 500 RPM 

With GST 

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

   3.3 - 4.8 g.m/sec: at idling 

   12.0 - 14.9 g.m/sec: at 2, 500 RPM 

OK or NG 

1. OK: GO TO 8.
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 .

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 4: Reading "POWER BALANCE" In "ACTIVE TEST" Mode

   Courtesy 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 5: Listening To Injector Operating Sound

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

OK or NG 

1. OK: GO TO 9.
2. NG: Perform trouble diagnosis for "INJECTOR CIRCUIT ".

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 on left bank (for DTC P0171), right bank (for DTC P0174).
4. Remove injector gallery assembly. Refer to "OUTER COMPONENT PARTS ".

   Keep fuel hose and all injectors connected to injector gallery.

   The injector harness connectors on right bank (for DTC P0171), left bank (for DTC P0174) 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. 

OK or NG 

1. OK: GO TO 10.
2. NG: Replace injectors from which fuel does not spray out. Always replace O-ring with new ones.
   Fig 6: Checking Fuel Injector Operation

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

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

: INSPECTION END