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).
   Fig 1: Checking Exhaust Gas Leak

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

   OK or NG 

   OK: GO TO 2.

   NG: Repair or replace.

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.

   OK or NG 

   OK: GO TO 3.

   NG: Repair or replace.

3. CHECK AIR FUEL RATIO (A/F) SENSOR 1 CIRCUIT FOR OPEN AND SHORT
   1. Turn ignition switch OFF.
   2. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
      • Air fuel ratio (A/F) sensor 1 (Bank 1) harness connector (1)
      • Air fuel ratio (A/F) sensor 1 (Bank 1) (2)
      • Air fuel ratio (A/F) sensor 1 (Bank 2) (3)
      • Air fuel ratio (A/F) sensor 1 (Bank 2) harness connector (4)
   3. Disconnect ECM harness connector.
   4. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
      TERMINAL CONTINUITY REFERENCE CHART
      
      

      Bank	A/F sensor 1 terminal	ECM terminal
      1	1	45
      	2	49
      2	1	53
      	2	57

      Continuity should exist  .

   5. Check harness continuity between the following terminals and ground.

      Refer to WIRING DIAGRAM .

      Fig 2: Location Of Air Fuel Ratio (A/F) Sensor 1 Harness Connectors

      Courtesy of NISSAN MOTOR CO., U.S.A.
      TERMINAL REFERENCE CHART
      
      

      Bank 1		Bank 2
      A/F sensor terminal	ECM terminal	A/F sensor terminal	ECM terminal
      1	45	1	53
      2	49	2	57

      Continuity should not exist  .

   6. Also check harness for short to power.

   OK or NG 

   OK: GO TO 4.

   NG: 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 "FUEL PRESSURE CHECK ".
   2. Install fuel pressure gauge and check fuel pressure. Refer to "FUEL PRESSURE CHECK ".

   At idling: Approximately 350 kPa (3.57 kg/cm ²  , 51 psi) 

   OK or NG 

   OK: GO TO  6.

   NG: GO TO 5.

5. DETECT MALFUNCTIONING PART

   Check the following.

   • Fuel pump and circuit (Refer to FUEL PUMP .)
   • Fuel pressure regulator (Refer to "FUEL PRESSURE CHECK ".)
   • Fuel lines (Refer to FUEL INJECTOR AND FUEL TUBE .)
   • Fuel filter for clogging

   Repair or replace.

6. CHECK MASS AIR FLOW SENSOR

   With CONSULT-III 

   1. Install all removed parts.
   2. Start engine and warm it up to normal operating temperature.
   3. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-III.

      At idling : 1.0 - 4.0 g.m/sec 

      At 2, 500 RPM : 4.0 - 10.0 g.m/sec 

   With GST 

   1. Install all removed parts.
   2. Start engine and warm it up to normal operating temperature.
   3. Check mass air flow sensor signal in Service $01 with GST.

      At idling : 1.0 - 4.0 g.m/sec 

      At 2, 500 RPM : 4.0 - 10.0 g.m/sec 

   OK or NG 

   OK: GO TO 7.

   NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to DTC P0101 MAF SENSOR .

7. CHECK FUNCTION OF FUEL INJECTORS

   With CONSULT-III 

   1. Let engine idle.
   2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-III.
   3. Check that each circuit produces a momentary engine speed drop.

   Without CONSULT-III 

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

   Clicking noise should be heard  .

   Fig 3: Checking Fuel Injector Operating Sound

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

   OK or NG 

   OK: GO TO 8.

   NG: Perform trouble diagnosis for FUEL INJECTOR .

8. CHECK FUEL INJECTOR
   1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
   2. Turn ignition switch OFF.
   3. Reconnect all harness connectors disconnected.
   4. Remove fuel tube assembly. Refer to FUEL INJECTOR AND FUEL TUBE .

      Keep fuel hose and all fuel injectors connected to fuel tube.

      The fuel injector harness connectors should remain connected.

   5. Disconnect all ignition coil harness connectors.
   6. Prepare pans or saucers under each fuel injector.
   7. Crank engine for approximately 3 seconds. Check that fuel sprays out from fuel injectors.

   Fuel should be sprayed evenly for each fuel injector  .

   Fig 4: Checking Fuel Injector Spray

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

   OK or NG 

   OK: GO TO 9.

   NG: Replace fuel injectors from which fuel does not spray out. Refer to "REMOVAL AND INSTALLATION ". Always replace O-ring with new ones.

9. CHECK INTERMITTENT INCIDENT

Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

INSPECTION END