Idle Speed Adjustment Procedures

Note

The curb idle and fast idle speeds are controlled by the EEC-IV processor and the idle speed control device and can not be adjusted.


Remember

A change in idle speed occured because of a problem elsewhere. You should only enter this procedure after you have eliminated the possible causes listed below:
^ Contamination within the throttle bore.

^ Contamination within the idle speed control device.

^ Throttle sticking or binding.

^ Engine not reaching operating temperature.

^ Vacuum leaks (air intake manifold, vacuum hoses, vacuum reservoirs, power brake booster where applicable, etc.).


Verify

^ Transmission in PARK or NEUTRAL.

^ Parking brakes applied (automatic brake release disconnected where applicable).

^ Wheels blocked.

^ Cooling system filled.

^ Engine at operating temperature.

^ Heater and accessories off.

^ Throttle lever is resting on the throttle plate stop screw (EFI only),

^ Ignition timing set to specification.

a. Perform EEC-IV diagnostics and resolve any vehicle malfunctions that are indicated by service output codes. (Ignore this step if you were sent here from an EEC-IV Pinpoint Test Step).

b. Engine off, disconnect the negative (-) terminal of the battery for three minutes minimum then reconnect it. (Omit this step if you are required to do it in Step 8 for Truck, or Step 9 for Passenger Car).

c. Start engine and stabilize for 2 minutes, then goose engine and let it return to idle. Lightly depress and release the accelerator and let engine idle. Does engine idle properly?

NOTE: If electric cooling fan comes on, wait until it turns off.

d. If engine does not idle properly, SHUT ENGINE OFF, Go to the appropriate adjustment procedure page. Follow the procedure from top of the page in sequence to the bottom of the page.