Chipster

I have a 2006 CTT with about 117K on it. When backing out of my driveway after an overnight cold start, the transmission will initially shift into Reverse without problem. The next gear change back into Drive takes up to 10-20 seconds before the driveline engages. If I slip it into neutral and give it a little rev, I will hear a click. When the revs drop I shift back into Drive and it engages, but still slow. Then at subsequent stop sign/red-light stops, it might take another 5-10 seconds before engaging into gear. I don't detect any slipping once engaged. It shifts normally (like butter) into all other gears. After a few minutes of driving, the delay from a stop also goes away. However, it will randomly shift itself from 2nd into 5th gear at a stoplight - but only after I release the brake pedal. When this happens, I shift up to Neutral then back to Drive and it goes back to 2nd immediately and drives normally again. Manually shifting doesn't seem to affect the issue.

All of this makes for great fun during early morning traffic.

I initially thought it might have a bad valve body, but after a discussion with Valve Body Pro in CA, they think the problem might be somewhere else - possibly the torque converter loosing fluid when it sits overnight and not properly engaging until it gets filled-up again. That makes some sense to my small brain. Note - the previous owner did the coolant pipes in 2017, and I have no idea if or how much coolant leaked into the bell-housing.

I recently had the transmission fluid level properly checked at a local European specialty shop - it was correct.

Thoughts?

Anybody change out a torque converter?

Thanks

cwheeler

When was the fluid last changed? Filter? I'd start with the simple "cheap" stuff first. I agree that it sounds like the valve body...

Chipster

The fluid & filter was changed in 2020. I'm running out of "cheap" options...

19psi

That pretty much rules out the torque converter. Also, if coolant ran down the back, it would ruin the seal causing a leak. No leaking trans fluid and proper level rules that out too.

Hearing a click (most likely solenoid) after revving in neutral and random 2 to 5 upshifts while sitting a stoplight sounds like an electrical issue to me. I'd start simple and take the cover off from around the shifter and make sure both magnets on that slide shade cover are still there...only takes a few minutes. A dime can easily get in there and tear things up.
I've also read about the transmission wire harness wicking up fluid and causing all kinds of strange issues.

When all this is happening, what happens if you switch your transfer case into low range and try driving away?

Chipster

Thanks for the feedback. I'm suspecting an electrical issue as well. Odd that it goes away when it warms up. I've pulled the shift cover and didn't see any issues, but it's worth another look.

I replaced the transfer case motor about a year ago and it has been functioning normally - until the other day. After a cold start I got a transfer case warning light. After re-starting, the light went out but when I attempted to engage the system, I got a rapid clicking from under the shift cover and the system would not engage. Again, after it warmed-up, it worked fine.

Also - I heard the jump to 5th gear is the system going into limp mode. No associated CEL.

I haven't ruled out that the car is possessed by evil spirits. I have a priest on standby.

19psi

I believe limp mode is 3rd gear on the Cayenne.

Also don't forget to check for water under the carpet.

Chipster

One of the first things I did after purchase was clean out the drains. Fortunately they were pretty clear of debris and there is no sign of moisture under the carpets.

Today I took the gear selector assembly apart to check the status of the magnets and general condition. I didn't see any issues so I cleaned and reassembled everything. The earlier issues still persist and have become worse with the colder weather.

Next step - take to my local independent shop. Maybe they can figure it out.

hopsis

You could buy or find someone with a VCDS cable. It will connect just fine to that transmission and You can do an "output test" with it. That actuates all the solenoids in the valve body and pretty much will tell You right away if one of them has gone bad. It will also show You input and output speeds that will help in finding out slipping parts.

Durametric propably has a similar function but I always use VCDS as it just is light years ahead in stuff like this.

phatz

Low fluid

Chipster

I hope it's something that simple. I had the fluid level checked and reset by a shop a few months ago, but that didn't fix the issue. I'm taking it back for a more in-depth diagnostic check. I will post the findings.

Chipster

Update - My shop finally got around to doing a full system scan. First, they agreed that the problem probably isn’t the valve body. Once the vehicle warmed-up, the transmission shifted normally. After clearing all the temporary stored codes, they drove it an got both input and output speed reference sensor faults. Since this sounds like an electrical issue, we decided to R&R new sensors, plus a new valve body wiring harness. So far, I was able to locate a new 14-pin VB harness and an output speed sensor. I’m scratching my head on the input speed sensor. The PET doesn’t show one and I’ve not been able to locate a part number.

Once I have the parts, the shop will do the install and refill the system.

Chipster

Fixed! After my mechanic finally got the Cayenne on the lift and removed the transmission pan, he found that transmission fluid was being wicked up the wiring harness and into the transmission control box - likely through a bad seal. This would explain the hot gear oil smell I was getting through the vents and probably the shifting issues. He replaced the valve body wiring harnesses, seals, speed sensor and wiring cable to the control box. Plus, he took the control box apart and cleaned it.

I’ve driven it about an hour through both city traffic and on the highway and the transmission feels perfect.

Hopefully this has resolved the trans issues. Now on to the brakes.