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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 103 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0301-P0304: Cylinder Misfire Detected (SOHC) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 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. Are any component DTCs set? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Perform a visual and physical inspection. Make any necessary repairs. Were any repairs necessary? If yes, go to step  6. If no, go to next step.
  4. With the engine idling, install a scan tool. Is the misfire current counter incrementing on the cylinder that had a misfire DTC? If yes, go to next step. If no, go to step  6.
  5. Turn engine off. Disconnect fuel injector harness connectors. Install the J-26792 Spark Tester on spark plug wire for cylinder that indicated a misfire. Disconnect other spark plug wire from the same ignition coil and install a jumper wire from the spark plug connector of the ignition coil housing to ground. Crank engine with remaining spark plugs cables still connected. Does spark tester spark? If yes, go to step  8. If no, go to step  9.
  6. Turn ignition on, with engine off. Review the Freeze Frame data. Note the parameters. Operate the vehicle within the Freeze Frame conditions and Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Is the misfire current counter incrementing on the cylinder that indicated a misfire? If yes, go to step  5. If no, go to next step.
  7. Was a repair made from the visual and physical inspection? If yes, go to step  30. If no, go to DIAGNOSTIC AIDS .
  8. Remove the spark plug from the misfiring cylinder. Exchange the spark plug with a spark plug from a known-good cylinder. Reconnect the fuel injector harness connector. Run the vehicle within the misfire conditions as noted from the Freeze Frame data. Is the misfire current counter incrementing on the cylinder that indicated a misfire? If no, go to step  13. If no, go to step  22.
  9. Remove spark plug cable from misfiring cylinder. Use a Digital Multimeter (DMM) in order to measure the resistance of spark plug cable. Is spark plug cable resistance less than 1000 ohms/inch? If yes, go to next step. If no, go to step  23.
  10. Remove ignition coil from cylinder that did not fire. Use a DMM in order to measure ignition coils secondary resistance. Is resistance within 5-8 k/ohms? If yes, go to next step. If no, go to step  24.
  11. Replace ignition coil with a known-good one. Crank engine. Inspect for spark. Did spark occur on spark tester? If yes, go to step  24. If yes, go to next step.
  12. Ensure that the ICM 6-pin harness connector is clean and tight. Repair as necessary. Where any repairs necessary? If yes, go to step  30. If no, go to step  25.
  13. Turn engine off. Disconnect 4 fuel injector harness connectors from the injectors. Install a J-34730-405 Injector Test light on the injector harness connector for the misfiring cylinder. Crank engine and note the test light. Does fuel injector test light blink? If yes, go to next step. If no, go to step  15.
  14. Perform Injector Coil/Balance Test Procedure. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. Is the fuel injector okay for the cylinder that had indicated a misfire? If yes, go to step  28. If no, go to step  29.
  15. Disconnect fuel injector test light. Connect a test light to ground, probe the misfiring cylinder fuel injector harness connector ignition positive voltage terminal. Crank the engine. Did the test light illuminate? If yes, go to next step. If no, go to step  27.
  16. Connect a test light to ground. Disconnect fuel injector harness connectors. Turn ignition on, with engine off. Probe the fuel injector harness connector control circuit terminal for the cylinder that indicated a misfire. Did the test light remain OFF? If yes, go to next step. If no, go to step  26.
  17. Connect the test light to B+. Probe the fuel injector control circuit terminal. Did the test light remain OFF? If yes, go to next step. If no, go to step  19.
  18. Inspect the fuel injector harness connector and the PCM harness connectors and connections for an open circuit. Are the connections okay? If yes, go to step  20. If no, go to step  21.
  19. Inspect for a short to ground in the fuel injector control circuit for the cylinder that indicated a misfire. Repair circuit as necessary. Did you find and correct the condition? If yes, go to step  30. If no, go to next step.
  20. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to step  30.
  21. Repair connector or connections. After repairs, go to step  30.
  22. Replace malfunctioning spark plug. When complete, go to step  30.
  23. Replace spark plug cable. When complete, go to step  30.
  24. Replace defective ignition coil. When complete, go to step  30.
  25. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to step  30.
  26. Inspect for a short to voltage in the misfiring cylinder fuel injector control circuit. Repair circuit as necessary. Did you complete the repair? If yes, go to step  30. If no, go to step  20.
  27. Repair open ignition positive voltage circuit for the fuel injector. After repairs, go to step  30.
  28. Inspect for a basic engine problem. When complete, go to step  30.
  29. Replace malfunctioning fuel injector. When complete, go to next step.
  30. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  31. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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