We have a 99 XJR . The original engine was replaced with a used engine with supercharger of the same year. When started it idled high while hunting for an idle. Showed a Throttle Body code. Drive it thinking it may even out but it never did. Brought it to jaguar dealer who spent several hours ($700 worth )testing sensors to finally say the ECM was bad and they did a hard restart of ecm and now the car won't start . It would be $6800 for a new ecm or I could send my original off to an online programmer , then bring it back in and they would program to the car. Does this make sense ? And if so where should we send it to be reprogrammed.

 

I hope you did not encounter the same dealer that another member of the forum met up with. They offered to carry out various repairs to her XKR for about $20,000.

The problem could have been with the throttle body of the replacement engine, but if it is the ECM I would rescue the car from the dealer and send the module to ASI for testing, and repair if needed. The cost would be under $500 if it is repairable, and if the dealer didn't mess up the software.

Automotive Scientific Inc. | Quality Rebuilt Automotive Electronics | Rogersville, TN

If you are going to rely on Jag dealers or even independent shops to repair and maintain your XJR it is liable to be an expensive proposition.

When you have time please visit the new member area and introduce yourselves. And please keep us informed of your progress with the car.

New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum

 

Thanks for your quick reply RJ . I should have mentioned in original question that after my nephew and I replaced the engine and got the throttle body code that we did change the throttle body from the original engine with no difference in performance . Then the car was driven in excess of 300 miles over a 2 week period with several stops and restarting the engine in hopes it may reset the failsafe mode with no difference. That is when we Drove it to the Northern Alabama Jag dealer to put on their equipment . I guess the big question is something doesn't seem right that we drove it in with an idle problem and received a call that it would need to be towed away. How do I trust that mechanic to touch the car again if I can get the ECM repaired. Also wondering what caused the ECM to "go bad " when it worked with previous engine , then this problem. Could it be a voltage supply that would cause a repaired one to do the same thing. Didn't see our car listed at ASI so will contact them today to see what they recommend.
Thanks again, Bob

 

If you disconnected the negative battery cable before disconnecting any cables elsewhere it is unlikely you could cause a problem. If not, a voltage spike could damage the ECM or other modules.
Your experience with the Jag dealer does not sound like a recommendation for having them do additional work.