Diagnostic Procedure

WARNING: This page is about a different car, the 2004 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FOR INTAKE AIR LEAK AND PCV HOSE
1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.
3. Check PCV hose connection.
OK or NG
1. OK: GO TO 2.
2. NG: Discover air leak location and repair.
CHECK FOR EXHAUST SYSTEM CLOGGING
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.
PERFORM POWER BALANCE TEST
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: Perform Power Balance Test With Consult-II
  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.
CHECK INJECTOR
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.
CHECK IGNITION SPARK
1. Remove ignition coil assembly from rocker cover.
2. Remove spark plug from ignition coil assembly.
3. Connect a known-good spark plug to ignition coil.
4. Place and of spark plug against a suitable ground 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 ".
CHECK SPARK PLUGS
Check the spark plugs and check for fouling, etc.

Fig 5: Checking Spark Plugs
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 7.
2. NG: Repair or replace spark plug(s) with standard type one(s).
CHECK COMPRESSION PRESSURE
Check compression pressure.

Refer to "CHECKING COMPRESSION PRESSURE ".

Standard: 1, 190 kPa (12, 1 kg/cm2, 172 psi)/300 RPM

Minimum: 990 kpa (10, 1 kg/cm2, 144 psi)/300 RPM

Difference between each cylinder: 98 kPa (1.0 kg/cm2, 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.
CHECK FUEL PRESSURE
1. Install all removed parts.
2. Release fuel pressure to zero. Refer to "FUEL PRESSURE CHECK ".
3. Install fuel pressure gauge and check fuel pressure.
  At idle: Approx. 350 kPa (3.57 kg/cm2, 51 psi)
OK or NG
1. OK: GO TO 10.
2. NG: GO TO 9.
DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to "FUEL PUMP CIRCUIT ".)
- Fuel pressure regulator (Refer to "FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY ".)
- Fuel lines
- Fuel filter for clogging
  1. Repair or replace.
CHECK IGNITION TIMING
Perform "BASIC INSPECTION ".

Fig 7: Target Idle Speed & Ignition Timing Specifications
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 11 (A/T models ULEV and M/T models).
  GO TO 12 (A/T models except ULEV).
2. NG: Adjust ignition timing.
CHECK HEATED OXYGEN SENSOR 1
Refer to "COMPONENT INSPECTION ".

OK or NG
1. OK: GO TO 14.
2. NG: Replace heated oxygen sensor 1.
CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector and A/F sensor 1 harness connector.
3. Check harness continuity between the following terminals. Refer to Wiring Diagram.
  
  Fig 8: Disconnecting A/F Sensor 1 Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 9: ECM & A/F Sensor Terminal Specifications
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should exist.
4. Check harness continuity between ECM terminals 16, 35, 56, 75 or A/F sensor 1 terminals 1, 2, 5, 6 and ground. Refer to Wiring Diagram.
  Continuity should not exist.
5. Also check harness for short to power.
OK or NG
1. OK: GO TO 13.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
CHECK A/F SENSOR 1 HEATER
Refer to "COMPONENT INSPECTION ".

OK or NG
1. OK: GO TO 14.
2. NG: Replace A/F sensor 1.
CHECK MASS AIR FLOW SENSOR
With CONSULT-II

Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT-II.

1.4 - 4.0 g.m/sec: at idling

4.0 - 10.0 g.m/see: at 2, 500 RPM

With GST

Check mass air flow sensor signal in MODE 1 with GST.

1.4 - 4.0 g.m/sec: at idling

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

OK or NG
1. OK: GO TO 16.
2. NG: GO TO 15.
CHECK CONNECTORS
Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds.

Refer to DTC P0101 MAF SENSOR and DTC P0102, P0103 MAF SENSOR .

OK or NG
1. OK: GO TO 16.
2. NG: Repair or replace it.
CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in "SYMPTOM MATRIX CHART ".

OK or NG
1. OK: GO TO 17.
2. NG: Repair or replace.
ERASE THE 1ST TRIP DTC
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 18.
CHECK INTERMITTENT INCIDENT
Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
1. INSPECTION END