Cuts Out/Misses

DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases, not normally felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or low speed.



PRELIMINARY CHECKS

^ Perform the careful visual/physical checks as described in "Preliminary Checks."

IGNITION SYSTEM

^ Check for cylinder miss: Refer to CHART C-4M, "Electronic Ignition (EI) System Misfire Diagnosis." Chart C-4M Electronic Ignition System Misfire Diagnosis

^ CHECK: Sparkplug(s).
- Insulator cracks.
- Wear.
- Improper gap.
- Burned electrodes.
- Heavy deposits.

^ Inspect ignition system for moisture, dust, cracks, etc. Spray spark plug cables with a water mist and check for shorts.

FUEL SYSTEM

^ CHECK: Fuel system - Plugged fuel filter, low pressure. Use CHART A-7. Chart C-7 EGR System Check
^ CHECK: For contaminated fuel.
^ CHECK: Injector drivers. Disconnect all injector harness connectors. Connect J 34730-2 Injector Test Light or equivalent between the harness terminal of each injector connector and note light while cranking If test light fails to blink at any one of the connectors, it is a faulty injector drive circuit harness, connector or terminal.
^ CHECK: Perform the "Injector Balance Test." Refer to CHART C-2A. Chart C-2A Injector Coil Test Procedure

ENGINE MECHANICAL

^ CHECK: Compression. Perform compression check on questionable cylinder(s) found above. If compression is low, repair as necessary.
^ CHECK: Base engine, worn camshaft lobes and valve timing. Repair as necessary.

ADDITIONAL CHECKS

^ CHECK: For EMI interference. A missing condition can be caused by Electromagnetic Interference (EMI) on the reference circuit. EMI can usually be detected by monitoring engine RPM with a Tech 1 scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present.
^ CHECK: Intake and exhaust manifold passage for casting flash.