Idle Speed: Adjustments

Throttle Sensor Connector:

NOTE: Before attempting to adjust the idle speed, perform a basic under-hood inspection. Check and verify the condition of the following:

^ Air cleaner
^ All vacuum hoses and ducting for the intake
^ EGR valve operation
^ Gaskets
^ Throttle valve plate and throttle bore for carbon
^ Throttle switch/sensor operation.


1. Disconnect the throttle sensor harness connector. Start the engine and warm it up until the water temperature indicator points to the middle of the gauge.
2. Operate the engine at 2000 rpm for 2 minutes under no load.
3. Race the engine 2 or 3 times under no load, then check the idle speed.
Idle speed should be:

USA M/T vehicles only.
650 ± 50 rpm.
Canadian M/T vehicles only.
750 ± 50 rpm.
All models with A/T transmissions.
800 ± 50 rpm (in "N" position).

If not correct, proceed to step 4.
4. Race the engine 2 or 3 times under no load then idle.
5. Verify ignition timing is 10° ± 2° B.T.D.C.

Idle Air Adjusting (I.A.A.) Unit:

6. Turn the idle adjusting screw (located on the idle air adjusting unit) to obtain the correct idle speed.
Idle speed should be:

All M/T 600 ± 50 rpm.
All A/T 725 ± 50 rpm.


7. Turn the engine off.
8. Reconnect the throttle sensor harness.
9. Race the engine 2 or 3 times under no load then idle.
Idle speed should be:

USA M/T vehicles only.
650 ± 50 rpm.
Canadian M/T vehicles only.
750 ± 50 rpm.
All models with A/T transmissions.
800 ± 50 rpm (in "N" position).

10. If not correct proceed to step 11.
11. Check the A.A.C. valve and harness, repair or replace as required.
12. The ECM may be the cause of a problem. This however is rarely the case.