Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Chevrolet >> 1996 >> Astro Van Cargo, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0300 - Engine Misfire Detected >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. If any other DTCs are set, go to next step. If no other DTCs are set, go to step 4).
  3. Diagnose affected DTC.
  4. Start engine and allow it to idle. Using scan tool, read MAP sensor voltage. If voltage is more than 4 volts, go to DTC P0108. If voltage is 4 volts or less, go to next step.
  5. Turn ignition off, and then on. Duplicate conditions required to set DTC. Using scan tool, read DTC PRESENT THIS IGNITION CYCLE. If scan tool displays DTC P0300, PRESENT THIS IGN, go to next step. If scan tool does not display DTC P0300, PRESENT THIS IGN, go to step 10).
  6. Install a spark tester on No. 1 spark plug wire. Disconnect fuel injector harness at intake manifold. Crank engine and check for spark at tester. Repeat procedure for each spark plug wire. If spark was okay on all wires, go to next step. If spark was not okay, go to step 11).
  7. Remove and check spark plugs for wear, excessive air gap, cracks or fouling. If spark plugs are okay, go to next step. If spark plugs are not okay, go to step 12).
  8. Perform A-4, INJECTOR CIRCUIT TEST under FUEL SYSTEM DIAGNOSIS in BASIC TESTING article. If fuel system is okay, go to next step. If fuel system is not okay, go to step 13).
  9. Diagnose and repair mechanical engine problem.
  10. DTC P0300 is intermittent. See DIAGNOSTIC AIDS.
  11. See IGNITION SYSTEM in BASIC TESTING article.
  12. Replace spark plug(s) and go to step 14).
  13. Repair as necessary and go to next step.
  14. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0300. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2).
  15. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
scientia non olet · About Mike's Workshop Manuals