Diagnosis 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 Leakage
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG

OK : GO TO 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

OK : GO TO 3.

NG : Repair or replace.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 CIRCUIT FOR OPEN AND SHORT

Turn ignition switch OFF.
Disconnect A/F sensor 1 harness connector and ECM harness connector.

Check harness continuity between ECM terminals and A/F sensor 1 terminals as follows.

Refer to WIRING DIAGRAM .

Fig 2: Identifying Brake Booster, Air Fuel Ratio Sensor And Air Fuel Ratio Sensor Connector

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

TERMINALS REFERENCE

A/F sensor 1	ECM terminal
1	16
2	75
5	35
6	56

Continuity should exist .

Check harness continuity between ECM terminals 16, 35, 56, 75 and ground, or A/F sensor 1 terminals 1, 2, 5, 6 and ground.
Refer to WIRING DIAGRAM .

Continuity should not exist .
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.

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.
DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to FUEL PUMP .)
- Fuel pressure regulator (Refer to "FUEL PRESSURE CHECK ".)
- Fuel lines
- Fuel filter for clogging
  Repair or replace.
CHECK MASS AIR FLOW SENSOR
With CONSULT-III
1. Install all removed parts.
2. 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 - 12.0 g.m/sec
With GST
1. Install all removed parts.
2. 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 - 12.0 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 grounds. Refer to "COMPONENT DESCRIPTION ".
CHECK FUNCTION OF FUEL INJECTOR
With CONSULT-III
1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT-III.
3. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT-III
1. Start engine.
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 .
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. Disconnect fuel injector harness connectors.
4. Remove fuel injector gallery assembly. Refer to "REMOVAL AND INSTALLATION ".
  Keep fuel hose and all fuel injectors connected to fuel injector gallery. 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 about 3 seconds. Make sure 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. Always replace O-ring with new ones.
CHECK INTERMITTENT INCIDENT
Perform "INTERMITTENT INCIDENT ".

INSPECTION END