Emission Control Systems: Adjustments

Idle Speed Setting:

1. Disconnect idle speed control-air bypass solenoid.
2. With transmission in Neutral or Park:

Run engine at 2500 rpm/30 seconds. Let engine idle for 2 minutes.

3. Place automatic transmission in Park manual transmission in Neutral.
4. Check/adjust idle rpm:

Turn the throttle plate stop screw to 625-725 rpm automatic transmission, 650-750 rpm manual transmission.


5. Engine off reconnect idle speed control-air bypass solenoid, verify the throttle is not stuck in the bore and linkage not preventing throttle from closing.
6. Start engine and stabilize for 2 minutes then goose engine and let it return to idle, lightly depress and release the accelerator. Let engine idle, if problem exists, refer to COMPUTER ENGINE CONTROLS/DIAGNOSTIC ROUTINES for other possible causes.

NOTE: A condition may occur where the engine rpm will oscillate. This can be caused by the throttle plates being open enough to allow purge flow. To verify this condition, disconnect the carbon canister purge line and plug it. If purge is present, the throttle plates must be closed until the purge flow induced idle oscillations stop.