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Home >> Hummer >> 2005 >> H2 4D Utility Pickup >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Troubleshooting >> Troubleshooting >> Cuts Out, Misses
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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 Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity.
Ignition System
  • 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 water.
  • Test for proper ignition voltage output with the J 26792  Spark Tester. See Special Tools .
  • Remove the spark plugs and inspect for the following:
    • Correct heat range
    • Wet plugs
    • Cracks
    • Wear
    • Improper gap
    • Burned electrodes
    • Heavy deposits
Refer to Spark Plug Inspection .
  • An improper spark plug gap will cause a driveability problem. Refer to Spark Plug Inspection . Gap the spark plugs using a wire gage gap tool. Refer to Spark Plug Replacement .
  • Determine the cause of the fouling before replacing the spark plugs.
  • Visually and physically inspect the secondary ignition for the following:
    • The ignition wires arcing to ground
    • The ignition wires for proper engagement to spark plug
    • The ignition coils for cracks or carbon tracking
  • Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
Engine Mechanical Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnostic procedures.
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) on the reference circuit can cause an engine misfire condition. A sudden increase in indicated RPM 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.