Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

Check For Intake Air Leak

Listen for intake air leak after MAF sensor. Check PCV hose connection. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

Check For Exhaust System Clogging

Stop engine. Visually check exhaust tube, 3-way catalyst and muffler for dents. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

Check EGR Function

Perform DTC CONFIRMATION TEST under DTC P1402: EGR FUNCTION. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

Perform Power Balance Test

With CONSULT-II
1. Perform POWER BALANCE in ACTIVE TEST mode with CONSULT-II. If there is any cylinder which does not produce a momentary engine speed drop, go to next step. If all cylinders produce a momentary engine speed drop, go to step 6 .
Without CONSULT-II
1. Start engine and let it idle. Individually, disconnect fuel injector harness connectors. If there is any cylinder which does not produce a momentary engine speed drop, go to next step. If all cylinders produce a momentary engine speed drop, go to step 6 .

Check Injector

Listen to each fuel injector. If every injector clicks, go to next step. If any injector does not click, repair injector or circuit as necessary. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. Perform DTC CONFIRMATION TEST to verify repair.

Check Ignition Spark

Turn ignition off. Disconnect ignition wire from spark plug. Connect a known good spark plug to ignition wire. Place end of spark plug against a suitable ground and crank engine. If spark is detected, go to next step. If no spark is detected, check ignition coil, power transistor and their related circuits. See IGNITION SYSTEM in SYSTEM & COMPONENT TESTING article. Repair as necessary. Perform DTC CONFIRMATION TEST to verify repair.

Check Spark Plugs

Remove spark plugs. Inspect spark plugs for fouling or other damage. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

Check Compression

Check compression. See BASIC DIAGNOSTIC PROCEDURES article. See COMPRESSION SPECIFICATIONS table. If compression is as specified, go to next step. If compression is not as specified, check pistons, piston rings, valves, valve seats and cylinder head gaskets. Repair as necessary. Perform DTC CONFIRMATION TEST to verify repair.

Check Fuel Pressure

Check fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be about 34 psi (235 kPa) at idle. If fuel pressure is okay, go to next step. If fuel pressure is not okay, repair fuel system as necessary. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. Perform DTC CONFIRMATION TEST to verify repair.

Check Ignition Timing

Perform BASIC INSPECTION. See ON-VEHICLE ADJUSTMENTS article. If ignition timing is okay, go to next step. If ignition timing is not okay, adjust ignition timing. Perform DTC CONFIRMATION TEST to verify repair.

Check HO2S1

Reconnect all harness connectors. Start engine and warm to normal operating temperature.
With CONSULT-II
1. Select MANU TRIG, and adjust TRIGGER POINT to 100% in DATA MONITOR mode with CONSULT-II. Select HO2S1 (B1)/(B2) and HO2S1 MNTR (B1)/(B2). Hold engine speed at 2000 RPM. Press RECORD. The following should occur:
  - HO2S1 MNTR (B1)/(B2) changes from RICH to LEAN to RICH 5 times in 10 seconds.
  - HO2S1 (B1)/(B2) voltage goes above 0.6V at least once.
  - HO2S1 (B1)/(B2) voltage goes below 0.3V at least once.
  - HO2S1 (B1)/(B2) voltage never exceeds 1.0V.
Without CONSULT-II
1. Measure voltage between ground and ECM terminal No. 94 (bank 1) or No. 62 (bank 2) by backprobing. Increase engine speed to 2000 RPM. The following should occur:
  - Voltage should cycle from less than .3 volt to more than .6 volt and back more than 5 times within 10 seconds.
  - Maximum voltage should be more than .6 volt at least once.
  - Minimum voltage should be less than .3 volt at least once.
  - Voltage should never exceed one volt.
If operation is as specified, go to next step. If operation is not as specified, replace HO2S1. Perform DTC CONFIRMATION TEST to verify repair.

Check MAF Sensor

Install all removed parts. Using CONSULT-II, select MASS AIR FLOW in DATA MONITOR mode. Using generic scan tool, select MODE 1, and read mass airflow. MAF reading should be 1.4-4.0 g/sec at idle and 5.0-10.0 g/sec at 2500 RPM. If MAF reading is as specified, go to next step. If MAF reading is not as specified, check connectors for rusted terminals or loose connections in the MAF sensor circuit for engine grounds. See DTC P0101, DTC P0102, DTC P0103 OR DTC P1102 . Repair as necessary. Perform DTC CONFIRMATION TEST to verify repair.

Check Rough Idle Symptoms

Check for possible causes of rough idle. See ROUGH IDLE under SYMPTOMS in TROUBLE SHOOTING - NO CODES article. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

Erase 1st Trip DTC

Some tests that were performed may cause a 1st trip DTC to set. Clear 1st trip DTC as necessary. Go to next step.

Check For Intermittent

Check for intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Perform DTC CONFIRMATION TEST to verify repair.

COMPRESSION SPECIFICATIONS

Application	Specification
Normal Compression Pressure	192 psi (13.5 kg/cm² )
Minimum Compression Pressure	168 psi (11.5 kg/cm² )
Maximum Variation Between Cylinders	14 psi (1.0 kg/cm² )