I purchased a 2004 XJ8 last April with 60,000 miles. Over the summer the transmission developed a pan leak. I purchased a oil change kit (filter and fluid), mechatronic seal adapter, and new bolts from California Transmission Supply. When I changed the fluid and set the level the car had 70,000 miles. Now with no signs of leakage and 85,000 miles I occasionally get a delay in upshift when starting out from a stop (usually when the car is cold). The car will hold the gear under light acceleration until I'm at ~5000 rpm and then upshift. Once it upshifts the rest of the shifts are smooth and once it shifts the car will take off from a stop normally. This happens maybe every 6th of 7th cold start. The rest of the time it runs normally.

Any thoughts?

 

I know the transmission has a "cold" adaptation in its programming so this could be quite normal in cold weather. Other cold weather drivers might know better but I wouldnt worry about the tranny - just your air struts!
Steve

 

It would be worth getting the TCM 'reflashed' with the latest transmission software. Any transmission shop that is familiar with ZF transmissions should be able to do it (as should any Jag agent, but at a Jag agent price).

 

I could see holding the gear longer than normal but not running at redline when enterning the highway at 60 mph.

 

A reflash may help, but I had very smooth shifts for the first 15,000 miles after the fluid change then hold the gear started to happen. Not sure what changed after 15,000 miles of operating with the new fluid. It was also smooth for the 10,000 miles I drove before the fluid change.

 

You might want to check fluid level again. Potentially, proper amount of fluid was not filled or overfilled. Both can cause issue of shifting overtime. Since you changed it once, it simples to swap out another five quarts of oil without changing the pan.

 

Update with additional information. While the lack of shifting usually happens when cold the other day I had driven ~80 miles (in 60F weather) at a fairly steady 60mph. Came into town and slowed to 30 mph then came to a red light. Stopped for 30 seconds and when I took off the car did not shift. Also when cold and its not shifting the torque converter seems to be locking up. I'll slowly accelerate to ~15 mph with no shift, lift off the throttle and the car slows drastically (like a manual transmission in first gear). Other times when its shifting well I lift off the throttle and the car slows but not as much as when its not shifting. If it does not **** I can generally force a shift by cycling the lever between 2 and 4.

I have not rechecked the fluid level (I'm waiting for ski season to end), but I do not think this is the root cause. The problem only happens 1 in 10 cold starts and has only happened once when warm running. At all other times it shifts smoothly, shifting appropriately if I accelerate gently and also if I really give it a lot of throttle.

When I changed the fluid I used a thermal couple wire bent into a hook and inserted into the fill port of the transmission to check the fluid temperature.

 

Harbor has a digital thermometer that works pretty well for this.