Diagnostic Procedure

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 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.
CHECK FOR INTAKE AIR LEAK
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 HEATED OXYGEN SENSOR 1 CIRCUIT FOR OPEN AND SHORT
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.
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:
  
  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.
DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to FUEL PUMP .)
- Fuel pressure regulator (Refer to Fuel Pressure Regulator Check .)
1. Repair or replace.
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.
  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 .
CHECK FUNCTION OF INJECTORS
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 " .
CHECK INJECTOR
1. Remove injector assembly. Refer to REMOVAL AND INSTALLATION .
  Keep fuel hose and all injectors connected to injector gallery.
2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Disconnect all injector harness connectors.
4. Disconnect all ignition coil harness connectors.
5. Prepare pans or saucers under each injectors.
6. Crank engine for about 3 seconds.
  Make sure fuel does not drip from injector.
OK or NG
1. OK (Does not drip.) GO TO 9.
2. NG (Drips.) Replace the injectors from which fuel is dripping. Always replace O-ring with new one.
CHECK INTERMITTENT INCIDENT
Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT " .
1. INSPECTION END