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 CHECKS
^ Check for cylinder miss: Refer to Chart C-4M. Chart C-4M Electronic Ignition System Misfire Diagnosis
^ Spark plug(s).
- Insulator cracks.
- Wear.
- Improper gap.
- Burned electrodes.
- Heavy deposits.

^ Inspect ignition system for moisture, dust, cracks, etc. Spray coils and plug wires with water mist and check for shorts.

FUEL SYSTEM CHECKS
^ Fuel system Plugged fuel filter. low pressure. Use CHART A-7. Related Tests, Information and Procedures
^ Contaminated fuel.
^ 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 connectors, it is a faulty injector drive circuit harness, connector or terminal.
^ Perform the injector balance test. Refer to CHART C-2A. Chart C-2A Injector Coil Balance Test Procedure

ENGINE MECHANICAL CHECKS
^ Compression. Perform compression check on questionable cylinder(s). If compression is low, repair as necessary.
^ Base engine. Remove rocker covers. Check for bent pushrods, worn rocker arms, broken valve springs, worn or broken camshaft lobes and incorrect valve timing. Repair as necessary.

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