Cuts Out/Misses

Symptom: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. The exhaust makes steady spitting sound at idle or low speed.

POSSIBLE CAUSE ACTION

IGNITION SYSTEM MALFUNCTION - Scope check Ignition System. Check SECONDARY CIRCUIT firing Kv and spark duration.
SEE IGNITION SYSTEM/OSCILLOSCOPE PATTERNS.

- Perform cylinder balance test.

- Remove spark plugs and inspect for: cracks, excessive wear, improper gap, burned electrodes, and wet or heavy deposits. Replace as necessary..

- Inspect distributor cap, rotor and spark plug wires for proper plug wire routing, crossfire between spark plugs (in cap) or wires, wires shorting to ground and rotor shorting to ground via distributor shaft.

- Check IGNITION TIMING for excessive spark advance or retard.
SEE Powertrain Management/Ignition System/Specifications.

ENGINE MECHANICAL MALFUNCTION - Perform compression and cylinder leak down test.
If compression readings are low or inconsistent check for improper valve timing (Timing belt alignment), sticking, or bent valves.

- Check for VACUUM LEAKS inspect intake manifold, gasket(s), and hoses.

FUEL SYSTEM MALFUNCTION - Check fuel pressure.

- Check for lean Air-Fuel mixture, (O2S Sensor output).

- Perform injector balance test.

- Check fuel quality.