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For 1990-2009 cars only

Cuts Out, Misses Symptom

Checks

Action

DEFINITION: A steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases. The exhaust has a steady spitting sound at idle, low speed or on hard acceleration.

Preliminary Checks

    • Refer to Diagnostic System Check - Vehicle .
    • Refer to Symptoms - Engine Controls .

Sensor Checks

    • Check the engine coolant temperature (ECT) sensor using a scan tool to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5°C (9°F) more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or in the sensor. Refer to Temperature Versus Resistance .
    • Inspect the mass air flow (MAF) sensor operation. Run the engine to normal operating temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan tool. If the MAF sensor reading is more than 3.5 g/s refer to DTC P0101 .

Fuel System Checks

    • Check for a restricted fuel filter or an incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Check for water contamination of the fuel.

Ignition System Checks

    • Check for an ignition system misfire:

        Important: Do not perform this test for more than 2 minutes in order to prevent damage to the catalytic converter.

        1. Start the engine.
        2. Remove one ignition coil at a time using insulated pliers.
        3. If there is an RPM drop on all cylinders (equal to within 50 RPM), refer to Rough, Unstable, or Incorrect Idle and Stalling .
        4. Check for spark on the suspected cylinders with a J 26792 Spark Tester or equivalent if there is no RPM drop on one or more cylinders.
        5. If there is no spark, refer to Engine Cranks But Does Not Run .
        6. If there is spark, inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .
    • Check the ignition system for moisture, dust, cracks, burns, etc.

Engine Mechanical Checks

    • Check for any of the following engine mechanical problems:
       - Faulty hydraulic lifter assemblies
       - Broken or weak valve springs
       - Incorrect valve timing
       - Incorrect or worn camshaft
    • Check the intake and exhaust manifold passages for casting flash.

Additional Checks

    • An engine miss condition can be caused by electromagnetic interference (EMI) on the reference circuit. EMI can usually be detected by monitoring the engine RPM with a scan tool. A sudden increase in RPM with little change in the actual engine RPM change indicates EMI is present. If a problem exists, check the routing of the secondary ignition wires and the high voltage components.
    • Verify the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Engine Controls Schematics .