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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 P0300: Engine Misfire Detected (DOHC) >> 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.
NOTE: Before clearing DTCs, record FREEZE FRAME/FAILURE RECORDS for reference with a scan tool. This data will be lost when you use CLEAR DTC information function.
  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, see 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  11. If no, go to next step.
  4. Start engine and idle the engine. Use the scan tool in order to observe the Misfire Current Counts. Operate the vehicle within the Freeze Frame data and the 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 .
  5. Is misfire present in all cylinders? If yes, go to next step. If no, go to step  9.
  6. Start and idle the engine. Compare the Manifold Absolute Pressure (MAP) voltage indicated by the scan tool with the typical scan data. Is the indicated value more than the typical value? If yes, go to DTC P0108: MAP SENSOR CIRCUIT - HIGH VOLTAGE . If no, go to next step.
  7. Perform the fuel system diagnosis. Did you find and correct the condition? If yes, go to step  11. If no, go to next step.
  8. Turn ignition off. Perform the Alcohol/Contaminants-in-Fuel Diagnosis. Did you find and correct the condition? If yes, go to step  11. If no, diagnose engine mechanical problem.
  9. Turn ignition off. Remove the fuel pump relay. Remove the ignition coil housing assembly keeping the ICM assembly connected to the harness connector. Important: Not grounding the ignition coil housing may cause an erratic spark. Install a jumper wire with clips on both ends from the top of the ICM to ground. Install the J-36012-A Spark Plug Jumper Wire Kit. Install a J-26792 Spark Tester on the #1 spark plug jumper wire. Ground the #4 spark plug jumper wire. The #4 wire is the companion to #1. Crank the engine with the remaining spark plug wires connected. Repeat previous steps by installing the spark tester on #4 and grounding #1. Do the same for the #2 and the #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, diagnose Electronic Ignition (EI) System.
  10. 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 next step. If no, diagnose engine mechanical problem.
  11. Clear the DTCs with a scan tool. 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.
  12. 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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