The engines covered in this manual contain sophisticated fuel injection systems, in which an engine control computer utilizes information from various sensors to control idle speed and air/fuel mixtures. Periodic adjustments are neither necessary, nor possible, on these systems. If a problem is suspected, please refer to Driveability & Emission Controls and Fuel System in this repair guide for more information on electronic engine controls and fuel injection.
See Figure 1
- Bring the engine up to normal operating temperature.
- Place the manual transmission in Neutral or automatic transmission Park. Firmly set the parking brake.
Idle speed is measured with the manual transmission in Neutral or the automatic transmission in Drive, with the wheels blocked and the parking brake ON.
- Check the curb idle speed, using a magnetic pickup tachometer suitable for diesel engines. The part number of the Ford tachometer is Rotunda 055-00108 or its equivalent. Adjust the idle speed to 600-700 rpm.
Always check the underhood emissions control information sticker for the latest idle and adjustment specifications.
- Place the transmission in Neutral (M/T) or Park (A/T) and momentarily speed up the engine. Allow the rpm to drop to idle and recheck the idle speed. Readjust if necessary.
No curb idle speed adjustment is possible, nor should any be attempted.Fast Idle
- Start the engine and bring it up to normal operating temperature.
- Place the transmission in Neutral (manual transmission) or Park (automatic transmission).
- Disconnect the wire from the fast idle solenoid.
- Apply battery voltage to activate the solenoid plunger.
- Speed up the engine momentarily to set the plunger.
- The fast idle should be 850-900 rpm. Adjust the fast idle by turning the solenoid plunger in or out.
- Speed up the engine momentarily and recheck the fast idle. Readjust if necessary.
- Remove the battery voltage from the solenoid and reconnect the solenoid wire.
No fast idle speed adjustment is possible, nor should any be attempted.