Please Help - C5 S6 Transmission Issue - Random Hard Jolt into different gear

[r.carter]

Quick plot points: No codes in the TCM/ECU, Trans rebuilt 24k ago.

Hello everyone, I tried to search the forums but didn't find anything that seemed to match my problem. If anyone can help me diagnose the problem, I would greatly appreciate it.

About 5 months ago I bought my 2002 S6 from across the country and drove it back to Seattle. About 1500 miles into the trip and there were no issues, but cruising down the freeway all of a sudden the car experienced a really violent jolt followed by a second and then....nothing. All seemed to be fine again. I proceeded to have this happen once every 300+ miles for the rest of the trip at random times, but was unable to purposefully get the car to exhibit the issue since it was so intermittent.

Fast forward a month and the issue turned into a once-per-trip issue and has remained that way ever since. Drive, Sport mode, or Tip, it doesn't matter. I turn on the car (doesn't matter if hot or cold), begin to drive, and within 10 minutes it will exhibit the issue. The car seems to violently upshift and then rapidly self-correct, but only if I maintain throttle. If not, it remains in the higher gear. So, for example, today I was in TIP mode, slightly accelerating in 2nd and boom the car jolted, shifted the 4th, I released the gas and it stayed in 4th with no secondary jolt. This seems to only happen once per trip and it is fairly early in the trip. Given, I have not done any long-distance trips with the car since then, but within 40 miles it happens once and then not until I end my trip and restart the car.

The car has 96k and the transmission was rebuilt at 72k. That being said, who knows what kind of rebuild they completed, my guess is as good as yours. I have checked multiple times with VCDS and the TCM/ECU doesn't throw any codes.

Is it the trans itself? TCM? Something completely unrelated? Any help would be greatly appreciated. If I can provide any other information, I would happily do so.

Cheers,
Ryan

[rollerton]

Sorry to say if you have no codes you have very very small chance it's either the valve body or the TCU. Considering how it seems to have a pattern and gets odd at a sort of predictable time then the trans is probably getting ready to have a bigger problem.
The miles on the trans are sort of irrelevant, mine only made it 5k miles before reverse failed.

But...timing is everything, I have a 5hp24 trans that worked perfect in all forward gears (and 50% power in reverse) and I may be getting it warrantied soon~ at which time it'll be for sale pretty cheap.

[r.carter]

Thank you for the reply. I worried that it was likely the valve body, but was hoping that there might be some better news.

Any way to see if it is the TCU? I imagine that would be easier/cheaper to replace?

I might be interested in your trans, but in all likelihood if mine fails I will become part of the #swapmafia. I had talked to Scotty about a tdi 6-speed, but we will see.

[G0to60]

Do you have anything plugged into the OBD port like a GPS or diagnostic reader?

The reason I ask is that I used to have one of those bluetooth diagnostic readers plugged into my allroad which is a TIP. On the freeway it would exhibit similar issues where it would hard shift to one gear and then back as if nothing happened. It only did this with the reader plugged into the OBD port and it has never done it when nothing is plugged in. I don't know why this happens but I've talked with a couple people that have had the same issue and it's "fixed" by unplugging something from the OBD port. Worth a shot.

[Scotty@Advanced]

I'd guess that the valve body needs to be replaced due to sticking pistons. Over time the pistons will score the valve body walls and get stuck. Pressure will continue to rise until the force is so great it pushes the piston to where it needs to be which causes jerky shifting.

Rebuilt valve bodys consist of enlarged piston bores and oversized hard anodized pistons..

[r.carter]

Do you have anything plugged into the OBD port like a GPS or diagnostic reader?

The reason I ask is that I used to have one of those bluetooth diagnostic readers plugged into my allroad which is a TIP. On the freeway it would exhibit similar issues where it would hard shift to one gear and then back as if nothing happened. It only did this with the reader plugged into the OBD port and it has never done it when nothing is plugged in. I don't know why this happens but I've talked with a couple people that have had the same issue and it's "fixed" by unplugging something from the OBD port. Worth a shot.

I am at a loss for words...

Maybe I should have known better, but I would have never guessed that it was my Valentine Savvy connector that was causing my issue, but alas, that appears it was the case. I have tried taking it in to shops around here, talking with people over the phone, and draining the trans/replacing the filter. I was about to drop $4,000+ to fix something that was not even broken, so simply saying "thank you" doesn't seem enough. Check your PMs.

[rollerton]

I would have never guessed that it was my Valentine Savvy connector that was causing my issue, but alas, that appears it was the case. I.

Seriously..?

Wow. I mean...wow? I seriously hope that was it.

[G0to60]

I'm just glad I could help out and it not cost a lot of money to fix. Cheap and easy fixes are the best. Especially with these cars.

Mine was a bluetooth thing for the Torque app and another person I talked to was using a GPS/Scan tool thing when similar symptoms cropped up. I'm not sure why having something plugged into the OBD port would cause this issue. Does having VAGCOM plugged in while driving cause this jolting? I don't have it yet so I can't test that out.