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Cuts Out, Misses

Cuts Out, Misses

Inspections Action
DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. This condition is not normally felt above 1,500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or low speed.
Preliminary
Fuel System
Sensor/System
  • Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature vs Resistance .
  • Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data List .
  • Inspect for throttle body tampering, excessive deposits, or damage.
  • Inspect for a vacuum leak.
  • Inspect the crankcase ventilation system for proper operation. Refer to Crankcase Ventilation System Inspection/Diagnosis in Engine Mechanical.
Ignition System
  • In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:
  • Inspect for proper secondary ignition voltage output with J 26792  HEI Spark Tester. See Special Tools .
  • Inspect the distributor cap and rotor. Refer to Distributor Inspection .
  • An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.
  • If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.
  • Inspect for damaged spark plug wires. Refer to Spark Plug Wire Inspection .
  • Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
  • Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.
Engine Mechanical
Additional Inspections
  • Inspect the exhaust system for possible restrictions. Inspect for the following:
    • Inspect the exhaust system for damaged or collapsed pipes.
    • Inspect the mufflers for heat distress or possible internal failure.
    • Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust in Engine Exhaust.
  • Electromagnetic interference (EMI) can cause an engine misfire condition. A sudden increase in indicated RPM parameter with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control circuits if a condition exists.
  • Inspect the intake manifold and the exhaust manifold passages for casting flash.