Rough, Unstable, or Incorrect Idle, Stalling

Definition: The engine runs unevenly at idle. If bad enough, the vehicle may shake. Also, the idle may vary in rpm. Either condition may be severe enough to cause stalling. Engine idles at incorrect speed.

POSSIBLE CAUSE ACTION

Throttle linkage sticking/binding ^ Check and adjust
Proceed to ADJUSTMENT PROCEDURES/ACCELERATOR CONTROLS.

Fuel Metering ^ Check air/fuel ratio, (verify O2 Sensor Voltage), refer to COMPUTERIZED ENGINE CONTROLS/DIAGNOSIS AND TESTING PROCEDURES.
^ Check fuel pressure, refer to DIAGNOSTIC CHARTS/FUEL SYSTEM PRESSURE TEST (CHART A-6).

Incorrect idle speed ^ Perform injector service (cleaning)
Proceed to MAINTENANCE PROCEDURES
^ Check Idle Air Control (IAC) Valve. Refer to COMPUTERIZED ENGINE CONTROLS/DIAGNOSIS AND TESTING PROCEDURES/DIAGNOSTIC CHARTS.
^ Check Minimum Idle Air Rate. Refer to ADJUSTMENT PROCEDURES/MINIMUM IDLE AIR RATE.

Vacuum Leak ^ Inspect vacuum hoses for proper routing and damaged lines
^ Check intake manifold, throttle body base and gasket