Rough, Unstable, or Incorrect Idle, Stalling

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


PCV valve malfunction Check PCV system. Refer to EMISSION CONTROL DEVICES/DIAGNOSIS, TESTING AND INSPECTION PROCEDURES/TESTING PROCEDURES/POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM.



Faulty canister purge valve Check evaporative system. Refer to Refer to EMISSION CONTROL DEVICES/DIAGNOSIS, TESTING AND INSPECTION PROCEDURES/TESTING PROCEDURES/EVAPORATIVE EMISSION CONTROL (EVAP) SYSTEM.


Restricted exhaust system Check Catalytic Converter. Refer to EMISSION CONTROL DEVICES/DIAGNOSIS, TESTING AND INSPECTION PROCEDURES/TESTING PROCEDURES/CATALYTIC CONVERTER.



Idle speed too low Check idle Idle Speed Control (ISC) valve.



Unmeasured air entering Check vacuum hoses,
intake system (vacuum leak) intake manifold gasket, throttle body gasket, power brake booster, injector O-Rings, etc. for vacuum leaks