Idle Speed: Adjustments

Fig. 2 Curb idle speed adjust. 5.0L Engine W/CFI:

Fig. 3 Curb idle speed adjust. V8-302 Engine W/EFI:

V8-302 W/EFI

On 1986 - 88 models, curb idle speed is not adjustable. Curb idle is controlled by the EEC-IV and the idle speed control unit. Perform the following procedure to set an initial adjustment.
1. Place transmission into Neutral or Park and apply parking brake.
2. Start and allow engine to reach normal operating temperature.
3. Connect a suitable tachometer onto engine as per manufacturer's instructions.
4. Place A/C-Heat selector switch to OFF position.
5. Turn ignition switch to OFF position, restart engine and increase engine speed to 2000 RPM on 1983 - 85 models and 1800 RPM on 1986 - 88 models for approximately 1 minute on 1983 - 85 models and 30 seconds on 1986 - 88 models. Decrease engine speed and allow speed to stabilize for approximately 15 seconds. On 4 wheel disc brake systems, depression of the brakes will result in variations in idle RPM proportional to the amount of pressure applied to the brakes. Idle speed should be set with the parking brake only applied, blocks placed behind the wheels and transmission placed in Reverse. Placing the transmission into Drive will automatically release the parking brake.
6. Check curb idle speed obtained.
7. If curb idle speed is too low, proceed as follows:
a. Turn ignition switch to OFF position.
b. Turn saddle bracket adjusting screw, Fig. 2, or throttle plate screw on 1986 - 88 models, Fig. 3, one full turn clockwise.
c. Check curb idle speed.
8. If curb idle speed is too high, turn saddle bracket adjusting screw or throttle plate screw counterclockwise until specified speed is obtained.