Idle Speed: Adjustments

Refer to Tune Up Specifications chart for curb idle speed settings. Curb idle speed is controlled by the EEC-IV processor and the idle speed control air bypass valve assembly. If engine curb idle RPM is not within specification after performing this procedure, refer to diagnostic procedures in ``Computerized Engine Controls'' section.
1. Place transmission in neutral and turn A/C-Heat selector to OFF position.
2. Run engine until it reaches normal operating temperature, then shut engine off.
3. Disconnect idle speed control air bypass valve power lead.
4. Start engine and run at 2000 RPM for 120 seconds.
5. If electric cooling fan comes on during idle speed set procedure, disconnect fan power lead.
6. Let engine idle and check that base idle RPM is 750 RPM.
7. Adjust engine RPM to specification by adjusting throttle plate stop screw.
8. Shut engine off, then reconnect power leads to idle speed control air bypass valve and the electric cooling fan.
9. Recheck idle speed. It should now be 900 RPM.
10. Ensure that throttle plate is not stuck in bore by moving throttle plate manually. If excessive idle speeds are experienced when driving vehicle on idle system, turn ignition switch to Off position and restart.