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 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
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.
CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
  
  Fig 2: Locating A/F Sensor 1 Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals.
  Refer to WIRING DIAGRAM .
  
  Fig 3: ECM Terminals And A/F Sensor 1 Terminals
  Courtesy of NISSAN MOTOR CO., U.S.A.
  1. Continuity should exist.
5. Check harness continuity between the following terminals and ground.
  Refer to WIRING DIAGRAM .
  
  Fig 4: ECM Terminals And A/F Sensor 1 Terminals
  Courtesy of NISSAN MOTOR CO., U.S.A.
  1. 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 ".
  1. At idling: Approximately 350 kPa (3.57 kg/cm ² , 51 psi)
OK or NG
1. OK: GO TO 5.
2. NG: GO TO 5.
DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to "FUEL PUMP CIRCUIT ".)
- Fuel pressure regulator (Refer to "FUEL PRESSURE CHECK ".)
- Fuel lines
- Fuel filter for clogging
  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.
    1. 3.0 - 9.0 g.m/sec: at idling
    2. 9.0 - 28.0 g.m/sec: at 2,500 RPM
  With GST
  1. Install all removed parts.
  2. Check mass air flow sensor signal in Service $01 with GST.
    1. 3.0 - 9.0 g.m/sec: at idling
    2. 9.0 - 28.0 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 grounds. Refer to "DTC P0101 MAF SENSOR ".
- CHECK FUNCTION OF INJECTORS
  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 5: CONSULT-II Display - "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.
    1. Clicking noise should be heard.
  OK or NG
  1. OK: GO TO 8.
  2. NG: Perform trouble diagnosis for INJECTORS, refer to "INJECTOR CIRCUIT ".
  Fig 6: Listening To Each Injector Operating Sound
  Courtesy of NISSAN MOTOR CO., U.S.A.
- CHECK 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 all injector harness connectors.
  4. Remove injector gallery assembly. Refer to "FUEL INJECTOR AND FUEL TUBE ".
    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.
    1. 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.
  Fig 7: Checking Injector Fuel Spray
  Courtesy of NISSAN MOTOR CO., U.S.A.
- CHECK INTERMITTENT INCIDENT
  Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
  1. INSPECTION END