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 30 MPH (48 km/h). The exhaust has a steady spitting sound at idle or low speed.

^ Perform careful visual.

^ Check for missing cylinder by:

1. Disconnect Idle Air Control (IAC) motor. Start engine. Remove one spark plug wire at a time using insulated pliers.

2. If there is an RPM drop on all cylinders (equal to within 50 RPM), go to ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING symptom. Reconnect IAC motor.

3. If there is no RPM drop on one or more cylinders, or excessive variation in drop, check for spark on the suspected cylinder(s) with J-26792 (ST-125) Spark Gap Tool or equivalent. If no spark, diagnose the ignition system. If there is spark, remove spark plug(s) in these cylinders and check for:
- Cracks
- Wear
- Improper Gap
- Burned Electrodes
- Heavy Deposits

^ Perform compression check on questionable cylinder(s) found above. If compression is low, repair as necessary.

^ Disconnect all injector harness connectors. Connect J-34730-2 Injector Test Light or equivalent 6 volt test light between the harness terms, of each injector connector and note light while cranking. If test light fails to blink at any connector, it is a faulty injector drive circuit harness, connector, terminal, or ECM.

^ Perform the Injector Balance Test. See CHART C-2A. Chart C-2A Injector Balance Test

^ Check spark plug wires by connecting ohmmeter to ends of each wire in question. If meter reads over 30,000 ohms, replace wire(s).

^ Visually check distributor cap and rotor for moisture, dust, cracks, burns, etc. Spray cap and plug wires with fine water mist to check for shorts.

^ Check for restricted fuel filter. Also check fuel tank for water.

^ Check for low fuel pressure. See CHART A-7.

^ Remove rocker covers. Check for bent pushrods, worn rocker arms, broken valve springs, worn camshaft lobes. Repair as necessary.

^ Check for proper valve timing.