Diagnostic Procedure

WARNING: This page is about a different car, the 2004 Nissan Titan. 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 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: CONSULT-II 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: Locating 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 in SYSTEM & COMPONENT TESTING - TITAN article.
Fig 3: Listening To Injectors
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK IGNITION SPARK
1. Turn ignition switch OFF.
2. Remove ignition coil assembly from rocker cover.
3. Remove spark plug from ignition coil assembly.
4. Connect a known-good spark plug to the ignition coil.
5. Disconnect all injector harness connectors.
6. Place end of spark plug against a suitable ground and crank engine.
7. 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 in SYSTEM & COMPONENT TESTING - TITAN article.
  Fig 4: Checking For Spark
  Courtesy of NISSAN MOTOR CO., U.S.A.

CHECK SPARK PLUGS

Remove the spark plugs and check for fouling, etc.

OK or NG

OK: GO TO 7.
NG: Repair or replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG TYPES table. .

Spark Plug Types

Make	NGK
Standard type	PLFR5A-11
Hot type	PLFR4A-11
Cold type	PLFR6A-11
Gap (nominal)	1.1 mm (0.043 in)

Fig 5: Checking Spark Plug

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

CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to CHECKING COMPRESSION PRESSURE in ENGINE MECHANICAL - TITAN - 5.6L article.
1. Standard: 1,520 kPa (15.5 kg/cm ², 200 psi)/200 RPM
2. Minimum: 1,324 kPa (13.5 kg/cm ², 192 psi)/200 RPM
3. Difference between each cylinder: 98 kPa (1.0 kg/cm ², 14 psi)/200 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 RELEASE in BASIC DIAGNOSTIC PROCEDURES - TITAN article.
3. Install fuel pressure gauge and check fuel pressure. Refer to FUEL PRESSURE CHECK in BASIC DIAGNOSTIC PROCEDURES - TITAN article.
  1. 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.
DETECT MALFUNCTIONING PART
Check the following.
- Fuel pump and circuit (Refer to FUEL PUMP CIRCUIT ) in SYSTEM & COMPONENT TESTING - TITAN article.
- Fuel pressure regulator. Refer to FUEL PRESSURE CHECK in BASIC DIAGNOSTIC PROCEDURES - TITAN article.
- Fuel lines
- Fuel filter for clogging
1. Repair or replace.
CHECK IGNITION TIMING
Check the following items. Refer to BASIC INSPECTION .

Fig 6: Ignition Timing Specifications
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 11.
2. NG: Follow the BASIC INSPECTION .
CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect A/F sensor 1 harness connector.
  
  Fig 7: Disconnecting 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 8: Identifying Harness Continuity Test 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 9: Identifying Harness Short To Ground Test 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 12.
  2. NG: Repair open circuit or short to ground or short to power in harness or connectors between ECM and A/F sensor 1.
CHECK A/F SENSOR 1 HEATER (BANK 1)/(BANK 2)
Refer to COMPONENT INSPECTION .

OK or NG
1. OK: GO TO 13.
2. NG: Replace (malfunctioning) A/F sensor 1.
CHECK MASS AIR FLOW SENSOR
With CONSULT-II

Check mass air flow sensor signal 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

Check mass air flow sensor signal in MODE 1 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 14.
2. NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds. Refer to DTC P0101 MAF SENSOR .
CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in SYMPTOM MATRIX CHART .

OK or NG
1. OK: GO TO 15.
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 16.
CHECK INTERMITTENT INCIDENT
Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .
1. INSPECTION END