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Home >> Chrysler >> 2002 >> Intrepid Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Multiple Cylinder Misfire, DTC P0301: Cylinder #1 Misfire, DTC P0302: Cylinder #2 Misfire, DTC P0303: Cylinder #3 Misfire, DTC P0304: Cylinder #4 Misfire, DTC P0305: Cylinder #5 Misfire Or DTC P0306: Cylinder #6 Misfire >> Testing

DTC P0300: Multiple Cylinder Misfire, DTC P0301: Cylinder #1 Misfire, DTC P0302: Cylinder #2 Misfire, DTC P0303: Cylinder #3 Misfire, DTC P0304: Cylinder #4 Misfire, DTC P0305: Cylinder #5 Misfire Or DTC P0306: Cylinder #6 Misfire: Testing

  1. Turn ignition on, engine not running. With the DRBIII®, select DTCs and RELATED FUNCTIONS. Read and record the FREEZE FRAME DATA. Select OBD II MONITORS. Read and record the MISFIRE SIMILAR CONDITIONS WINDOW DATA. With these screens, attempt to duplicate the condition(s) that has set this DTC. When the vehicle is operating in the SIMILAR CONDITIONS WINDOW, refer to the WHICH CYLINDER IS MISFIRING screen. Observe the WHICH CYLINDER IS MISFIRING screen for at least one minute. Is the DRBIII® counting misfires at this time? If yes, go to next step. If no, go to step  8.
  2. With the DRBIII®, read the FREEZE FRAME DATA. Use the FREEZE FRAME DATA and attempt to determine the cause of the Misfire DTC. In the FREEZE FRAME DATA, is the LOAD VALUE over 50 percent and the operating temp normal? If yes, check secondary ignition, components and perform a cylinder leakage test. If no, go to next step.
  3. Check for any of the following conditions/mechanical problems:
    • Engine vacuum must be at least 13 in. Hg in Neutral.
    • Engine valve timing must be within specification.
    • Engine compression must be within specification.
    • Cylinder leakage test must be within specification.
    • Camshaft lobes must not be worn.
    • Weak valve springs.
    • Engine Positive Crankcase Ventilation (PCV) system must flow freely.
    • Torque converter stall speed must be within specification.
    • Power brake booster must have no internal leaks.
    • Fuel injectors must be free of restrictions.

    Are there any engine mechanical problems? If yes, repair as necessary. If no, go to next step.

  4. Start the engine and allow the engine to idle. With the DRBIII®, read the FREEZE FRAME DATA. Use the FREEZE FRAME DATA and attempt to determine the cause of the Misfire DTC. In the FREEZE FRAME, are the adaptive fuel percentages greater than plus or minus 15 percent? If yes, check fuel delivery. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING article. If no, go to next step.
  5. With the DRBIII®, read the FREEZE FRAME DATA. Use the FREEZE FRAME DATA and attempt to determine the cause of the Misfire DTC. In the FREEZE FRAME DATA, is the engine RPM over 3000 and the operating temp normal? If yes, test CMP and CKP Sensor Signals with Lab Scope, check valve timing, and perform running vacuum test. If no, go to next step.
    6. NOTE: Anything that affects the speed of the crankshaft can cause a misfire DTC.
  6. Check the following additional items as possible mechanical problems:
    • Injector Harness Connectors
    • PCM Power Or Grounds
    • Restricted Exhaust
    • Intake Restriction
    • Damaged Trigger Wheel
    • Contaminated Fuel
    • Carbon Build-Up On Valves
    • Spark Plugs
    • Accessory Drive Belt

    Repair mechanical problems as necessary. If no mechanical problems exist, go to next step.

    7. NOTE: Before continuing, check the PCM harness connectors for corrosion, damage or terminal push out. Repair as necessary.
  7. There are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
    8. NOTE: An intermittent problem may have been caused by moisture in the secondary ignition.
    WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.
  8. The conditions that set the DTC are not present at this time. The following may help in identifying the intermittent condition. With the DRBIII®, select DTCs AND RELATED FUNCTIONS. Read and record the FREEZE FRAME DATA. Select OBD II MONITORS. Read and record MISFIRE SIMILAR CONDITIONS WINDOW DATA. With these screens, attempt to duplicate the condition that has set the Misfire DTC. While using FREEZE FRAME DATA, pay particular attention to the DTC setting conditions, such as speed, temp, load, and MAP vacuum. Does the misfire reoccur? If yes, restart diagnostics beginning with step  2. If no, test is complete.
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