September 30: LEMON manuals is back up on a temporary server! Slowness is possible
Rough Or Unstable Idle
- Use stethoscope to verify fuel injector operating noise.
- Ensure fuel system pressure is correct.
- Check EGR valve condition and operation.
- Verify ignition timing is correct.
- Check PCV valve.
- Check mass airflow sensor.
- Check coolant thermosensor for correct resistance.
- Check bypass air control valve.
- Check for cracks and poor connections (vacuum leaks) at airflow meter or throttle body.
- Check HO2S for fluctuating 0.1-1.0 volt output while increasing and decreasing engine RPM.
- Verify throttle position sensor adjustment and resistance value.
- Check purge valve function.
- Check for poor fuel quality.