Moving this over after posting in the wrong forum.

I have a 2008 Cayenne S and have noticed an odd trend. Over time, the shifting of the car seems to change, not as smooth, hesitates to down shift, just a clunker feel in general. When I have the car serviced, I just did a couple of days ago, it goes back to a smooth shifting fun machine. I assume as part of the service the ECU is flashed and the shifting algorithm is reverted from what is has "learned" over the past few months to the default. But this is just a guess. Has anyone else experienced this behavior? Does the car "learn" over time and adjust is driving characteristics? If so, can I flash the ECU myself on a regular basis?

One other data point. After my coolant pipe glue failure\fix, the car started throwing a P2181 error for the thermostat. The engine temp has been running fine so I haven't spent the cash to get it replaced. But that could also be the cause of the poor shifting performance if the program is altering behavior based on the error.

 

If you have a Durametric or PIWIS you can reset the transmission adaptation, if that doesn't work I'd recommend doing a trans flush and fill along with the filter.

 

Also, how do you know your engine temp is fine. You should monitor it via a tool in the obd2 port. When my dash gauge shows normal temperature and virtually no movement, the actual coolant temp can fluctuate between 180-215 degrees F. The dash gauge is too heavily buffered to be useful and is really more like an idiot light if it actually gets high, the actual coolant temp is really high.

 

I picked up my 955 at the end of January with 121,500 miles on it. I noticed the gearbox wasn’t as smooth as my previous Jag along with a considerable thump when shifting down from 5th to 4th so I asked the dealer to do a gearbox oil change when they had it back replacing the ABS sensors that had given up on the motorway.

They changed the oil and within 100 miles of having it back the gearbox stuck itself in 5th and wouldn’t move out of it at all. That was a fun drive getting it back to the garage...

15 weeks later and I still don’t have it on my drive - had 5 courtesy cars in the meantime though and they’re installing a replacement gearbox. Apparently the flush and oil change dislodged some metal which got stuck and didn’t do the original box any good whatsoever.

If you can keep it ticking over through software without upsetting any of the internal parts then I’d stick with that route given my experience here!