In July 2013, my wife began complaining of rough upshifts in her 2006 XK8 at approximately 67,000 miles. We DIY'ed a ZF pan drop, sleeve change, and refill with Lifeguard 6. While shift quality improved somewhat, it took a ZF Adaptations Drive Cycle procedure at the Greensboro dealership ($150) to completely restore the shift quality to normal....

In April 2016, she began complaining of the same rough upshifts at approximately 101,000 miles. This time we did just a ZF drain-and-fill using Mercon SP. And again, while shift quality improved somewhat, it took another ZF Adaptations Drive Cycle procedure at the Greensboro dealership (another $150) to completely restore the shift quality to normal....

The Greensboro dealership did not want to perform this second ZF Adaptations Drive Cycle procedure, believing that it could significantly shorten the life of the internal clutches. I consulted with ZF Tech Support in Chicago, and they advised me that at 101,000 miles I had little to lose by trying the procedure again if I was facing a ZF rebuild anyway. So I called the Greensboro dealership back, informed them of my lengthy phone conversation with ZF Tech Support, and they agreed to do the second procedure....

We DIY'ed one more ZF drain-and-fill in November 2016 at approximately 106,000 miles using Mercon SP simply to ensure that at least 85% of the ATF in the car is now relatively fresh Mercon SP....

The car is now approaching 112,000 miles and the ZF continues to perform normally. She has not complained again about the shift quality. I keep my fingers crossed that it stays that way....

 

Time was they were allegedly made of chocolate. Looking good (or at least acceptable) so far. Stick with it.

Many dealers know less than owners...

 

I know it might sound strange that I am giving an update considering how old this thread is but I really haven't driven the car much and I am pretty busy with work so I only get to dive into maintenance and repair once in a while.

So after using the software to reset everything on the TCM, I noticed a big improvement over time in the bump going from 2nd down to first pulling up to stop signs etc. However, the transmission fault issues continue so I wanted to give you an update on my thoughts with this:

1- I find the issue is primarily entered around 5th gear and if you are not really careful with kick down, you will almost assuredly throw a fault.
2 - I am now using the J-gate exclusively and not using any type of auto shifting. This has resulted in very consistent response from the transmission unless I demand it to do something outside of the norm. As example, if you really put your foot it in, the TCM still gets involved and I had the TCM throw a fault once while in J-gate.
3 - I have done a bunch of new online research and I have decided my next triage step will be to replace the valve body seals. I am 99.9% that this is a valve body issue in some way. Either seals are leaking or there are issues with actuators.

There are three seal types that I am changing out - shown in the attached photo. These are the most common to show issues so it makes sense to do those first. Logic would dictate that I should just rebuild the valve body while I have it all out and I haven't completely ruled that out yet. If I see obvious signs of degradation on the seals I am replacing, I will risk putting it back together without doing any rebuilding of the valve body but if the seals all seem solid and pliable (unlikely), I will go ahead and rebuild the valve body while it's all exposed. The only reason I wouldn't rebuild it is because I want to know the root cause of these symptoms in the event it can save someone else a lot of time and money if I am able to narrow this down.

Stay tuned for the updates as I have them

 

Issue has been resolved - please see this thread

https://www.jaguarforums.com/forum/x...-intel-203967/