This past Sunday on my way to the Queen's English Car Show about 10 minutes from my home, my 2010XKR started idling erratically at first, then started misfiring horribly, and was putting unspent fuel through the tailpipes with tons of grey smoke from the unburnt fuel. I got to the show and immediately had my mechanic pick up the car on his flat bed and take it to the shop, it was not drivable and would not stay started more than a few seconds. These were the exact same symptoms I had on the car four or five months ago in my own driveway, and at that time, after doing some diagnostics, he reprogrammed the ECU's memory and the car returned to normal. So, he did the same thing, yesterday, and presto, car is running perfectly fine.

The question is what could cause the the failure of the ECU where it could still be reflashed to work again? That is the question the mechanic is worried about because he and I are afraid it will happen again without warning as it has the previous two times. He suspects there might be a faulty wiring harness but is grasping for ideas. I thought I'd throw it out there and see if any of you have had any similar experiences or have any ideas.

I drove the car home from the shop tonight, and it's as if nothing ever happened.

 

It does sound strange considering it is a relatively new car. Has the ECU ever been tuned . Also seems like reflashing might also cause a potential issue. Was the reflash done using a Jaguar system or an aftermarket one. There could be a corrupt bit in the reflash. Might consider seeing if the dealer could reflash it with the Jaguar code. Hopefully you won't need a new ECU.

 

Did it have the same issue when your mechanic arrived after it had time to cool off from sitting overnight? Or was it still that way just minutes prior to the reflash?

Dave

 

Scary - maybe you can find a used engine ECU on eBay or wherever, and have your mechanic install it and program it? The loss of memory seems like an issue internal to the ECU and not an external wiring issue.

 

well someone's got to say it, may as well be me. How old is your battery??

I have nothing else to offer. Carry on.

 

Well the harness can certainly be the cause as can other things. Can you tell us the long list of codes it would have thrown when she started behaving badly?

 

I recall someone finding the connector to their ECU was a bit corroded due to water ingress, causing strange problems.