04 XJR surging + new Transmission

It’s been many years since I have visited this site having sold my 6.2L e type. I’m currently looking at a 04 XJR with 155k miles. It’s a 2 owner car that has even serviced by the dealer until it needed a new transmission which has been replaced by an independent transmission shop. Since then It has developed a surging at 35-40 mph. No one has been able to resolve it including the dealer. I’m reluctant to buy it… any advice is greatly interested.

Here are the steps you need to do with this car… big ones in the opposite direction.
Unless you have a masochistic tendency.
Sorry can’t really help but if the dealer hasn’t been able to solve it then it could be a deep seated problem, I take it these are still the Merc boxes?
Just looked on another forum and came up with this;
Yep, it’s pretty common, it’s the torque converter lock up clutch engaging & disengaging repeatedly during warm up, there is a TSB for it, as already said, the TCM reflash is supposed to fix it they should also flash the PCM as part of the process, but if it fails the only cure is new torque converter, many people live with it, I’ve never seen anyone report a total transmission failure 'cos of it. Some people have reported the effect is reduced in sport mode.

Thanks so much for the reply… makes sense to me.

As above. I believe these use the ZF 6 gearbox, which isn’t great for reliability.

Yeah sounds like the torque converter. Well overdue replacement.

No the XJR uses the Mercedes transmission the ZF isn’t rated high enough.

The transmission was changed from the 5 speed Mercedes to the 6 speed ZF in 2003, which was one of the main reasons I recently purchased a 2002.

When it changed from x308 to x350 the XJR box went from Merc to ZF6