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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 250 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0301-P0304: Cylinder Misfire Detected >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Start the engine. Allow the engine to idle or operate within the conditions listed in the Freeze Frame/Failure Records. Monitor all of the misfire counters using the scan tool. Are any of the misfire current counters incrementing? If yes, go to next step. If no, go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  3. Are any DTCs other than DTC P0300 set? If yes, go to step  10. If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  4. Can any abnormal engine noise be heard? If yes, diagnose engine mechanical problem. See appropriate article in ENGINES. If no, go to next step.
    5. NOTE: DO NOT remove the Ignition Control Module (ICM) and connector from the ignition coil housing.
    NOTE: Not grounding the ignition coil housing may cause erratic spark.
  5. Turn ignition switch to OFF position. Remove the fuel pump relay. Remove the ignition coil housing assembly. Connect a jumper wire between the IC module and a good ground. Connect the Ignition System Diagnostic Harness (J 36012-A), or equivalent. Install Spark Tester (J 26792), or equivalent, on the affected cylinder spark plug jumper wire. Ground the companion to the affected cylinder spark plug jumper wire. Crank the engine with the remaining spark plug jumper wires connected. Does the spark tester spark? If yes, go to step  7. If no, go to next step.
  6. Inspect the affected cylinder spark plug boot for a missing or damaged ignition coil spring. Did you find and correct the condition? If yes, go to step  16. If no, go to step  15.
  7. Remove the spark plug from the cylinder that indicated a misfire. Inspect the spark plug. Does the spark plug appear to be okay? If yes, go to next step. If no, go to step  9.
  8. Turn ignition switch to OFF position. Remove the spark plug boots from the affected coil. Inspect the affected cylinder boot for damage or missing spring, and replace as necessary. Did you find and correct the condition? If yes, go to step  10. If no, go to next step.
  9. Is the spark plug oil or coolant fouled? If yes, diagnose engine mechanical problem. See appropriate article in ENGINES. If no, go to step  11.
  10. Is the spark plug gas fouled? If yes, go to step  12. If no, go to step  11.
  11. Does the spark plug show any signs of being cracked, worn, or improperly gapped? If yes, go to step  13. If no, go to next step.
  12. Perform injector coil test and injector balance test procedure. See FUEL INJECTOR COIL TEST under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING 2.2L - ALERO, CAVALIER, GRAND AM & SUNFIRE article. Did you find and correct the condition? If yes, go to step  16. If no, diagnose engine mechanical problem. See appropriate article in ENGINES.
  13. Replace or gap the spark plug. If an improper gap is found, be sure to gap the spark plugs using a wire type gauge. After repair, go to step  16.
  14. Replace the faulty spark plug. After repair, go to step  16.
  15. Replace ignition coil housing. After repair, go to step  16.
  16. Was the customer concern the MIL flashing? If yes, go to next step. If no, go to step  18.
  17. Operate the vehicle at 2500 RPM for 4 minutes. Operate the vehicle within the Conditions for Running the DTC P0420 as specified in the supporting text. See CONDITIONS FOR RUNNING DTC  in DTC P0420: TWC SYSTEM - LOW EFFICIENCY. Does the DTC run and pass? If yes, go to next step. If no, go to DTC P0420: TWC SYSTEM - LOW EFFICIENCY .
  18. Using a scan tool, clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  19. Using scan tool, observe the CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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