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Home >> Nissan-Datsun >> 2003 >> Sentra SE-R Spec V >> Repair and Diagnosis >> External Pages >> Different car >> Section 12 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0301: Random/Multiple Cylinder No. 1 Misfire Detected, DTC P0302: Random/Multiple Cylinder No. 2 Misfire Detected, DTC P0303: Random/Multiple Cylinder No. 3 Misfire Detected Or DTC P0304: Random/Multiple Cylinder No. 4 Misfire Detected >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport and 2002 Isuzu Rodeo. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ON-BOARD DIAGNOSTIC II SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
  2. Start engine and allow it to idle. Using scan tool, read and record FREEZE FRAME data. Operate vehicle within conditions noted in FREEZE FRAME data. Using scan tool, read MISFIRE CUR # display for each cylinder. If MISFIRE CUR # is increasing (indicating a misfire currently occurring) for any cylinder, go to next step. If MISFIRE CUR # is not increasing, go to DIAGNOSTIC AIDS  .
  3. Check vacuum hoses for splits, kinks, or improper connections. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  4. Check intake manifold, injector "O" rings, EGR valve, and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  5. Check PCV valve for improper installation or damaged hose. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  6. Remove ignition coils. Check ignition coils for cracks or carbon tracking. If a problem is found, replace damaged ignition coils. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  7. Install a spark tester on spark plug wire at spark plug end for cylinder indicating most severe misfire. Crank engine and check for crisp, Blue spark at tester. Repeat procedure for each affected cylinder. If spark is okay on all cylinders, go to step  12 . If spark is not okay on any cylinder, go to next step.
  8. Remove spark plug(s) associated with misfiring cylinder(s). Check spark plugs for excessive fouling. If spark plugs are excessively fouled, diagnose and repair mechanical engine problem. If spark plugs are not excessively fouled, go to next step.
  9. Check spark plug insulation for cracks, carbon tracking or other damage. If a problem is found, replace faulty spark plug(s). After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  10. Replace ignition control module. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  11. Check PCM injector, power and sensor grounds for clean, tight connections, and proper location. See WIRING DIAGRAMS article. See Figure . If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  12. Perform fuel pump pressure test. See FUEL PUMP PRESSURE TEST under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If a problem was found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem was found, go to next step.
  13. Check for fuel contamination. If fuel is contaminated, repair condition causing contamination. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If fuel is okay, go to next step.
  14. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  15. Diagnose mechanical engine problems such as faulty or incorrect camshaft timing, leaking valves or piston rings, sticky valves, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing, leaking head gasket, or loose or broken motor mounts. If a problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
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