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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 134 (Engine Control System - Self-Diagnostics) >> Diagnostic Tests >> DTC P0301, P0302, P0303, P0304: Cylinder Specific Misfire Detected >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Install scan tool. Start engine. Monitor MISFIRE CURRENT CYL. NO. data parameter for all engine cylinders on the scan tool. Does scan tool indicate a misfire in any cylinder? If yes, go to step  5. If no, go to next step.
  3. Use scan tool to clear DTCs. Using the scan tool, place vehicle into CHECK MODE. See SERVICE BAY TESTS  under SELF-DIAGNOSTIC SYSTEM. Operate vehicle within freeze frame conditions as specified. Monitor MISFIRE CURRENT CYL. NO. data parameters on scan tool. Is a cylinder specific misfire DTC P0301-P0304 set or does scan tool indicate a misfire in any cylinder? If yes, go to step  5. If no, go to next step.
  4. The fault is not present. Are there any DTCs stored that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to DIAGNOSTIC AIDS .
  5. Is a DTC P1300, P1305, P1310, or P1315 present? If yes, go to DTC P1300, P1305, P1310, P1315: IGNITION COIL PRIMARY FEEDBACK CIRCUITS . If no, go to next step.
  6. Disconnect ignition coil of misfiring cylinder. Remove ignition coil of misfiring cylinder. Connect harness connector of the removed ignition coil. Install Spark Tester (J 26792), or equivalent, at the end of spark plug boot of removed ignition coil. Crank engine while observing spark tester. A crisp, blue spark should be observed. Was a crisp, blue spark present on every engine revolution? If yes, go to step  8. If no, go to next step.
  7. Turn ignition OFF. Exchange ignition coil. Replace ignition coil of suspected faulty cylinder with an ignition coil from a normally operating cylinder. Install spark tester at the end of the spark plug boot of ignition coil. Check for spark as performed in step 6)  . Did the test indicate a crisp, blue spark while cranking the engine? If yes, go to step  15. If no, go to step  16.
  8. Perform a visual and physical inspection of the ignition coil boot for the following conditions:
    • Water intrusion or moisture.
    • A corroded or damaged electrical terminal.
    • Carbon tracking.
    Repair the condition or replace ignition coil or spark plug as necessary. Was a repair necessary? If yes, go to step  15. If no, go to next step.
  9. Remove spark plug from misfiring cylinders. Check spark plugs for correct operation and good performance. Repair or replace spark plug(s) as necessary. Was a faulty spark plug condition found and repaired? If yes, go to step  18. If no, go to next step.
  10. Turn engine OFF. Disconnect fuel injector of each misfiring cylinder. Install Fuel Injector Test Light (J 34730-2B), or equivalent, into fuel injector harness connector of a misfiring cylinder. Check fuel injector circuit by observing the test light while cranking the engine. Repeat action in step 3)  and test in step 4)  for each misfiring cylinder. Did the fuel injector test light blink for every test while cranking the engine? If yes, go to next step. If no, go to FUEL INJECTOR CIRCUIT DIAGNOSIS under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.
  11. Perform the Fuel Injector Coil Test and the Fuel Injector Balance Test procedures. See FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C) and FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article. Did any fuel injectors require replacement? If yes, go to step  18. If no, go to next step.
  12. Turn ignition switch to OFF position. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article. Install a fuel pressure gauge. See FUEL GAUGE under FUEL SYSTEMS in REMOVAL & INSTALLATION - 1.8L VIBE article. Install scan tool. Turn ignition switch to RUN position, engine OFF. Select FUEL PUMP in ENGINE OUTPUT CONTROLS menu of scan tool. Command fuel pump ON, using scan tool. Observe fuel pressure indicated by fuel pressure gauge with the fuel pump running. Is fuel pressure 44-50 psi (301-347 kPa)? If yes, go to next step. If no, diagnose fuel system. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.
  13. Check a fuel sample for the following concerns: Replace fuel as necessary. See FUEL SYSTEM CLEANING under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article. Was a repair necessary? If yes, go to step  18. If no, go to next step.
  14. Visually and physically check the following for vacuum leaks:
    • Intake manifold gasket.
    • Vacuum lines, hoses, and fittings.
    Check for incorrect vacuum hose routing. Repair as necessary. Check PCV system for an incorrectly operating or leaking PCV valve. See POSITIVE CRANKCASE VENTILATION under EMISSION CONTROLS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 1.8L VIBE article. Replace PCV valve as necessary. Did you replace a part or perform a repair? If yes, go to step  18. If no, go to step  17.
  15. Replace faulty ignition coil. After repair, go to step  18.
  16. Check malfunctioning ignition coil circuits for the following conditions:
    • An open in ignition coil ground circuit.
    • An open in positive voltage supply circuit.
    • An open in trigger signal circuit.
    • No trigger signal generated by PCM.
    Repair as necessary. After repair, go to step  18.
  17. Check for the following engine mechanical conditions:
    • A worn or faulty camshaft.
    • Any leaky or sticky valves.
    • Any excessive valve deposits.
    • Any weak valve springs.
    • Incorrect valve timing.
    • Faulty rocker arm operation.
    • An intake manifold runner leak or obstruction.
    • Any broken or worn piston rings.
    • A leaking head gasket.
    Repair as necessary. Was a basic engine mechanical concern found and repaired? If yes, go to step  18. If no, go to DIAGNOSTIC AIDS .
  18. Use scan tool to clear DTCs. Operate vehicle within freeze frame conditions that set the DTC. Monitor MISFIRE CURRENT CYL NO. data parameters on scan tool. Did a DTC set or did scan tool indicate a misfire in any cylinder? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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