Hello everybody.
I have a 04 xj8 that is appoaching 100k on the clock. I did a recent tranny drain and pan replacement about 5k ago.
I bought that car with 75k on the clock and since then when the car has been sitting over night the engine rpms bounce up and down about 1000 rpm in the top two gears for the first ten mins or so until car is warmed up (click on the picture and watch video ). I know other have had this problem as well and I was wondering if there has been a solution found yet? All help is appreciated!

 

Hi Scuba

Yes, there definitely IS a cure, because I just had the cure done by the local Jaguar main agent in Wilmslow, England. They told me that they have to report the VIN number to Jaguar, and are then given a number key to allow them to download the transmission software settings from Jaguar.

All my hunting has now gone. I had it when I bought the car last year in May, but only got round to fixing it about 6 weeks ago. I think a lot of owners just put up with it. No charge for the software, but the dealer labour is chargeable, in my case, about 30 minutes.

 

I had mine flashed out of pocket.
It lasted about a week.
I know a retired Jag tech, he said it does not always work. Sometimes the valve body has to be replaced as the TCM is integral to the valve body.

I don't drive the car that much, mostly when I have to fill the gas tank. I just hit the gas hard to downshift and it usually goes away.
Has something to do with the adaptive learning.
Different drivers in the same car may have different experiences. The new TCM has a broader learn.