Curb Idle Speed

Fig. 5 Throttle plate adjust. 4-97.6 & 4-116 W/EFI:

4-97.6 & 4-116 W/EFI

Curb idle speed is adjusted by the EEC IV and the idle speed control (ISC) system. The following procedure is an initial curb idle speed setting with the ISC disconnected. Refer to Tune Up Specifications chart for curb and fast idle speeds.

1. Place transmission into Neutral or Park.
2. Start and allow engine to reach normal operating temperature, then switch ignition OFF.
3. Disconnect and plug both vacuum lines from EGR solenoid.
4. Disconnect power lead electrical connector from ISC.
5. Install a suitable tachometer onto engine as per manufacturer's instructions.
6. Start and operate engine at 2000 RPM for approximately 1 minute. Ensure electric cooling fan comes ON.
7. Apply hand brake.
8. Place transmission into Neutral on manual transaxle models or Drive on automatic transaxle models.
9. Check and if necessary adjust initial curb idle speed within 1-1/2 minutes by turning throttle plate adjusting screw, Fig. 5.

Fig. 8 Curb idle speed adjust. 4-116 Less EFI:

4-116 Less EFI

1. Place transmission in Neutral or Park, with A/C-Heater selector in the OFF position.
2. Start and allow engine to reach normal operating temperature. Ensure engine timing is to specification.
3. Disconnect and plug vacuum hose from thermactor air control valve bypass.
4. Position fast idle adjustment onto second step of fast idle cam, then operate engine until cooling fan comes ON, Fig. 8.
5. Depress throttle slightly to allow fast idle cam to rotate, and check curb idle speed. Engine cooling fan must be operating when checking curb idle speed.
6. Place transmission in neutral or park, and recheck curb idle speed. Readjust curb idle speed if necessary.