Idle timing adjusts the proper speed of engine rotation during vehicle stop (closed throttle). Proper idle is important for proper engine operation and fuel economy. Idling speed also affects the function of engine-driven accessories, such as the alternator, air conditioning compressor, engine cooling fan, and water pump. Idle is adjustable on 1984-1986 carburetor-equipped models of the Jeep Cherokee. On 1987 and later fuel-injected Cherokee models, idle is controlled by the engine control computer and is not adjustable as part of routine tune-ups and maintenance. What’s more, if you think your Cherokee XJ is not bright enough, just upgrade it with the Jeep Cherokee xj led headlights, while they come with high beam, low beam, drl and turn signals will be better, so that you do not need upgrade the turn signal lights as well.
Things you will need
Small (1/4-inch or adjustable) wrench or pliers
See More Instructions
Connect the tachometer to the vehicle following the tachometer manufacturer’s instructions. Exact attachment depends on the make and model of your tachometer. Make sure the cables do not touch the fan and other moving parts of the motor.
Set the parking brake. Shift the automatic transmission out of “park” or the manual gearbox out of “neutral.”
Start the engine and let it run until it reaches normal operating temperature (upper coolant hose will be hot). Turn off the engine as well as the air conditioning.
Disconnect the vacuum line from the sol-vac actuator carburetor (four-cylinder models) or the exhaust gas recirculation valve (V6 models). Plug the disconnected vacuum lines.
Idling Check and adjust.
engine running. Check idle speed with tachometer. For manual transmissions, the gear lever must be in “neutral.” For automatic transmissions, the gear lever must be in “drive.” Have an assistant turn to “drive” while holding the brake pedal.
Compare the idle speed to the specifications on the vehicle information emission control label, located in the engine compartment. Normal idle speed is 700 to 750 rpm. Use this value if the label is missing or damaged. If the idle speed is correct, you are done. Shut off the engine, disconnect the tachometer and reconnect the vacuum lines.
Adjust the idle speed by turning the idle adjustment screw on the carburetor (V6 models) or by turning the 1/4-inch nut on the sol-vac vacuum actuator (four-cylinder models). Turn clockwise to increase idle speed, counterclockwise to decrease idle speed.
Shut off the engine, disconnect the tachometer and reconnect the vacuum lines.