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 visual and physical checks as described in Diagnosis By Symptom/Preliminary Checks. - Important Preliminary Checks

CYLINDER BALANCE TEST
^ Perform misfire check. Refer to Chart C-4B Misfire Check. Chart C-4B Misfire Check

ENGINE MECHANICAL
Check: Compression. Perform compression check on questionable cylinder(s). If compression is low, repair as necessary.

Check: Base engine. Remove rocket covers, check for bent pushrods, worn rocker arms, broken valve springs, work camshaft lobes and valve timing, repair as necessary.

ADDITIONAL CHECKS
Check: Distributor vent system. Refer to Chart C-4C Distributor Vent System Check. Chart C-4C Distributor Vent System Check

Check: For Electromagnetic Interference (EMI). An engine miss condition can be caused by EMI on the reference circuit. EMI can usually be detected by monitoring engine RPM with a scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present. If the problem exists, check routing of secondary ignition wires and check distributor ground circuit.

Check: Intake and exhaust manifold passage for casting flash.

Check: Spark plugs. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary.