Two idle speeds are controlled by a solenoid on models without both automatic transmission and air conditioning. One is normal curb idle speed (solenoid energized). The other is base idle speed (solenoid de-energized), which is 200 rpm lower than curb idle speed and prevents dieseling when the ignition is turned off. On cars with air conditioning the solenoid is energized when the air conditioning is on to maintain curb idle speed.
- With the engine at normal operating temperature, air cleaner on, choke open, and the air conditioner off, attach a tachometer to the engine following the manufacturer's instructions. Apply the parking brake, block the rear wheels, disconnect and plug the PCV hose at the vapor canister and the vacuum advance hose at the distributor.
- For cars without automatic transmission and air conditioning, turn the idle solenoid in or out to obtain, the curb idle speed stated in the tune-up specification chart, then disconnect the wire from the solenoid.
- With the automatic transmission in Drive or the manual transmission in Neutral, set the base idle speed to 200 rpm lower than the curb idle speed by turning the 1 / 8 " hex screw located in the end of the solenoid. Reconnect the wire to the solenoid.
- Cars with both automatic transmission and air conditioning must have a green wire with double white stripe connected to the idle solenoid, NOT a brown wire. Correct this if necessary.
- With the air conditioning off and the automatic transmission in Drive turn the 1 / 8 " hex screw in the end of the solenoid until fully bottomed.
- Turn the entire solenoid assembly to obtain 950 rpm.
- Adjust the curb idle speed by turning the hex screw out to obtain the correct rpm. (See tune-up specifications chart.)
- Check the ignition timing and adjust if necessary. Readjust the solenoid assembly and curb idle speed if necessary.
- Stop the engine, remove the tachometer, and connect the PCV and vacuum hoses.
Refer to the Vehicle Emission Control Information sticker on the vehicle for the latest specification information and idle speed adjustment procedure.
On these models, the carburetor mixture and idle speed are adjusted by the Computer Command Control (CCC) System. However, it is possible to adjust the basic idle speed as follows:
- Set the parking brake and block the drive wheels.
- Verify ignition timing.
- Disconnect the EGR vacuum source at the carburetor and cap the port.
- Disconnect and plug the vacuum hoses for the canister purge and purge control at the canister.
- Attach a tachometer to the engine following the manufacturer's instructions.
- With the engine running, adjust the idle speed screw to the rpm specified on the vehicle emission control information label.
- Unplug and reconnect the vacuum hoses.