Cuts Out/Misses

Definition: A steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases. The exhaust has a steady spitting sound at idle, low speed or on hard acceleration.

Preliminary Checks

^ Refer to "Important Preliminary Checks." Testing and Inspection

^ Check for fuel spray from both fuel injectors. Refer to Fuel Injector Coil Test/Fuel Injector Balance Test Procedure.
Fuel Injector Balance Test

Ignition System Checks

^ Check for a cylinder misfire:

1. Start the engine. Allow the engine to stabilize then disconnect the Idle Air Control (IAC) motor.

2. Remove one spark plug wire at a time, using insulated pliers. Notice: Do not perform this test for more than 2 minutes, as this may cause damage to the catalytic converter.

3. If there is a RPM drop on all cylinders (equal to within 50 RPM), go to the "Rough, Unstable or Incorrect Idle, Stalling" Symptom Table.

4. Reconnect the IAC valve with the ignition "OFF."

5. Check for spark on the suspected cylinder(s) with the J 26792 spark tester, or equivalent, if there is no RPM drop on one or more cylinders, or excessive variation in drop.

6. If there is no spark, refer to Table A-3. Table A-3 Engine Cranks But Does Not Run

7. If there is spark, remove the spark plug(s) in these cylinders and check for the following:

- Terminal screw - bent, loose (rotate and pull)

- Ceramic Insulator - cracks, tracking, deposits (red or black dust)

- Tip Insulator - cracks, tracking, deposits (oil, carbon, glazing, fuel additive), loose (rattles)

- Center electrode - loose (wiggles side to side)

- Platinum pads - missing, wear, gap size (too large or too small)

^ Check the spark plug wire resistance (should not exceed 30,000 ohms).

^ Check the distributor rotor and the distributor cap.

^ If the previous checks did not find the problem, visually check the following:

- The ignition system for moisture, dust, cracks, burns, etc.

- With the engine running, spray the plug wires with a fine water mist to check for shorts.

Engine Mechanical Check

^ Check the engine for the following:

- Proper valve timing

- Bent push rods

- Worn rocker arms

- Broken or weak valve springs

- Worn camshaft lobes

- Refer to the appropriate service manual.

^ Check the intake and exhaust manifold passage for casting flash. Refer to the appropriate service manual.

Fuel System Checks

^ Check the fuel system for a plugged fuel filter, low fuel pressure, etc. Refer to Table A7-B. Table A-7B Fuel System Diagnosis (Fuel Pressure Check)

^ Check for water contamination in the fuel.