Diagnostic Procedure

1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.

OK or NG

1. OK : GO TO 2.
2. NG : Discover air leak location and repair.

Stop engine and visually check exhaust tube, three way catalyst (manifold) and muffler for dents.

OK or NG

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

With CONSULT-II 

1. Perform "POWER BALANCE" in "ACTIVE TEST" mode.
2. Is there any cylinder which does not produce a momentary engine speed drop?
   Fig 1: CONSULT-II Diagnosis Function Display

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

Without CONSULT-II 

When disconnecting each injector harness connector one at a time, is there any cylinder which does not produce a momentary engine speed drop?

Fig 2: Disconnecting Injector Harness Connector

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

Yes or No

1. Yes : GO TO 4.
2. No : GO TO  7.

Does each injector make an operating sound at idle?

Yes or No

1. Yes : GO TO 5.
2. No : Check injector(s) and circuit(s). Refer to "INJECTOR CIRCUIT ".
   Fig 3: Checking Injector

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

1. Remove ignition coil assembly from rocker cover.
2. Remove spark plug from ignition coil assembly
3. Connect a known good-spark plug to the ignition coil.
4. Place end of spark plug against a suitable ground and crank engine.
5. Check for spark.

OK or NG

1. OK : GO TO 6.
2. NG : Check ignition coil, power transistor and their circuits. Refer to "IGNITION SIGNAL ".
   Fig 4: Checking Ignition Spark

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

Remove the spark plugs and check for fouling, etc.

OK or NG

1. OK : GO TO 7.
2. NG : Repair or replace spark plug(s) with standard type one(s).
   Fig 5: Checking Spark Plugs For Fouling

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

Check compression pressure. Refer to CHECKING COMPRESSION PRESSURE .

Standard: 1, 275 kPa (13.0 kg/cm ²  , 185 psi)/300 RPM 

Minimum: 981 kPa (10.0 kg/cm ²  , 142 psi)/300 RPM 

Difference between each cylinder: 98 kPa (1.0 kg/cm ²  , 14 psi)/300 RPM 

OK or NG

1. OK : GO TO 8.
2. NG : Check pistons, piston rings, valves, valve seats and cylinder head gaskets.

1. Install all removed parts.
2. Release fuel pressure to zero. Refer to "FUEL PRESSURE RELEASE ".
3. Install fuel pressure gauge and check fuel pressure. Refer to "FUEL PRESSURE CHECK ".

   At idle: Approx. 350 kPa (3.57 kg/cm ²  , 51 psi) 

OK or NG

1. OK : GO TO  10.
2. NG : GO TO 9.

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 the following items. Refer to "BASIC INSPECTION ".

OK or NG

1. OK : GO TO 11.
2. NG : Follow the "BASIC INSPECTION ".

Refer to "COMPONENT INSPECTION ".

OK or NG

1. OK : GO TO 12.
2. NG : Replace malfunctioning heated oxygen sensor 1.

With CONSULT-II 

Check mass air flow sensor signal 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 

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 13.
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 items on the rough idle symptom in "SYMPTOM MATRIX CHART ".

OK or NG

1. OK : GO TO 14.
2. NG : Repair or replace.

Some tests may cause a 1st trip DTC to be set.

Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".

1. : GO TO 15.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

1. : INSPECTION END