Have you had any repairs done recently to the vehicle? If you have you may just need to reset the ECM adaptations for it to run properly again? Here is a service bulletin to reseting the adaptations?
V8 XJ Series/XK8
1997 MY-ON XK8 Range
1998 MY-ON V8 XJ Series
Driveability Concerns After Repair - Resetting ECM Adaptation
Issue: After repairing an engine management problem, the vehicle may still not run properly because the ECM strategy has adapted to an extreme rich or lean limit while attempting to compensate for the previous problem. This bulletin outlines a procedure for resetting the ECM adaptation to a base setting.
Action: ENGINE CONTROL MODULE (ECM) ADAPTATION
To expedite the adaptive learning process for some functions of the ECM, perform the following procedure: Warning: Perform this procedure with the vehicle on a firm surface (not on a lift) after ensuring that no danger exists to surrounding personnel or property.
Caution: Do not exceed the engine speeds and time durations listed below.
1. Apply the parking brake, and allow the engine to reach normal operating temperature with the selector lever in P.
2. Press the A/C button to turn the climate control off.
3. Apply the service brakes, and move the transmission selector lever to D. Perform steps 4-7 with the brakes applied and the transmission selector lever in D.
4. Allow the engine to idle for an additional 2 minutes.
5. Gradually raise the engine speed to 950 RPM. Hold this speed for 45 seconds.
6. Raise the engine speed to 1200 RPM. Hold this speed for 45 seconds.
7. Raise the engine speed to 1500 RPM. Hold this speed for 30 seconds.
8. Allow the engine to return to idle. Move the selector lever to P and allow the engine to idle for 2 minutes to cool the transmission fluid. Switch off the engine.
Let me know if this helps you out?
Wednesday, July 27th, 2011 AT 3:47 AM