Rough Unstable Idle

The engine runs unevenly. If bad enough, the car may shake. The engine idle may hunt or fluctuate in rpm and may be bad enough to stall.

POSSIBLE CAUSE ACTION

At all times

PCV malfunction See Positive Crankcase Ventilation



At operating temperatures

Faulty canister purge 1. See Evaporative Emissions System
If OK, go to step 2.
2. Check Evaporative System electronic controls.



Restricted exhaust See Catalytic Converter



Idle speed too low Check operation of any idle speed controlling device. Check and adjust idle speed.