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Home >> Chevrolet >> 2001 >> Cavalier LS, 2.2 4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (Engine Controls Self-Diagnostics - 2.4L) >> Diagnostic Tests >> DTC P0300: Engine Misfire Detected >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire 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 other DTCs set? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  3. Turn ignition off. Perform a visual and physical inspection. If a problem is found, repair as necessary. Did you find and correct any conditions? If yes, go to step  27 . If no, go to next step.
  4. Start and idle engine. Use scan tool in order to observe the Misfire Current Counts. Are any Misfire Current counts incrementing? If yes, go to step  6 . If no, go to next step.
  5. Operate vehicle within the Freeze Frame data and Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Are any Misfire Current counts incrementing? If yes, go to next step. If no, go to DIAGNOSTIC AIDS  .
  6. Is misfire present in all cylinders? If yes, go to next step. If no, go to step  11 .
  7. Perform Fuel System Diagnosis. Did you find and correct the condition? If yes, go to step  27 . If no, go to next step.
  8. Turn ignition off. Perform the Alcohol/Contaminants in Fuel Diagnosis. Did you find contaminated fuel? If yes, go to step  10 . If no, go to next step.
  9. Inspect for basic engine problems. Did you find and correct any conditions? If yes, go to step  27 .
  10. Perform fuel system cleaning. When complete, go to step  27 .
    11. NOTE: Not grounding the IC module assembly may cause erratic spark.
  11. Turn ignition off. Remove fuel pump relay. Remove Ignition Control (IC) assembly keeping the IC assembly connected to the harness connector. Connect a fused jumper from the IC module assembly to ground. Install J-36012-A Ignition System Diagnostic Harness. Install a J-26792 Spark Tester on the No. 1 spark plug jumper wire. Ground the No. 4 spark plug jumper wire. The No. 4 wire is the companion to No. 1. Crank engine with remaining spark plug wires connected. Repeat this step by installing the spark tester on No. 4 and grounding No. 1. Do the same for the No. 2 and No. 3 spark plugs. Make sure the companion wire is grounded. Does the spark tester spark on all cylinders? If yes, go to next step. If no, go to step  13 .
  12. Turn ignition off. Inspect for malfunctioning spark plugs in the cylinders that indicated a misfire. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  27 . If no, go to step  9 .
  13. Disconnect PCM connector. Reconnect the J-26792 on the spark plug jumper wire that did not spark. Ground the companion spark plug jumper wire. Turn ignition on, with engine off. Connect a test light to B+. Momentarily touch the affected IC timing control circuit at the PCM connector. A spark should be present when the test light is removed from the circuit. Did the spark tester spark? If yes, go to step  23 . If no, go to next step.
  14. Turn ignition off. Remove spark plug jumper wires from the affected cylinder and the companion at the coil housing. Connect a DMM between the secondary ignition coil terminals. Is resistance within 4-8 k/ohms? If yes, go to next step. If no, go to step  16 .
  15. Remove ignition coil housing from cover. Disconnect ignition coil harness connector at the IC module. Connect 2 test lights to B+. Probe the affected ignition coil control terminal at the IC module with one of the test lights. Turn ignition on, with engine off. DO NOT leave test light connected to PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the ignition control module. Momentarily touch the affected IC timing control circuit at the PCM connector with one test light while monitoring the other test light. Does the test light blink? If yes, go to step  17 . If no, go to step  18 .
  16. Remove ignition coil housing. Disconnect ignition coil connector from the IC module. Remove affected ignition coil from housing. Retest the resistance between the secondary terminals of the coil. Is the resistance within 4-8 k/ohms? If yes, go to step  20 . If no, go to step  21 .
  17. Turn ignition off. Test the coil control circuit between the IC module and affected ignition coil for an open, short to ground, short to voltage, or poor connection at ignition coil or at IC module If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  27 . If no, go to step  19 .
  18. Turn ignition off. Disconnect IC module 11-pin connector. Test the affected IC timing control input circuit between the IC module and the PCM for an open, short to ground, or short to voltage. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  27 . If no, go to step  24 .
    19. NOTE: Carefully handle the ignition coil connectors to avoid spark arching from the terminals and causing the fuse to open which would lead to a misdiagnosis.
  19. Disconnect the ignition coil connector from the affected ignition coil. Reconnect the ignition coil connector to the IC module. Connect a test light to ground. Turn ignition on, with engine off. Probe the ignition feed circuit at the coil connectors one at a time with the test light. Does the test light illuminate for both circuits? If yes, go to next step. If no, go to step  22 .
  20. Inspect the affected cylinder and the companion for corrosion or damage to the spark plug boot, ignition coil springs, or ignition coil housing. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  27 . If no, go to next step.
  21. Inspect the ignition coil and the PCM terminals of the affected coil for poor connections. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  27 . If no, go to step  25 .
  22. Turn ignition off. Repair the open in the ignition 1 circuit as necessary. After repairs, go to step  27 .
  23. Turn ignition off. Inspect the PCM connector and terminals for poor connections. Did you find and correct the condition? If yes, go to step  27 . If no, go to step  26 .
  24. Replace the IC. When complete, go to step  27 .
  25. Replace the affected ignition coil. When complete, go to step  27 .
  26. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  27. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start the 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 .
  28. Turn ignition on, with engine off. Using scan tool, observe the stored information and 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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