Originally Posted by Jon8138

I have a 2012 A6 3.0T currently at stage 1+ and about 430hp. Trans is a ZF 8 speed. Just bought the car a few weeks ago and did not notice a stumble or studder at low RPM on the test drive. Now that I've been driving the car I've noticed that in either 2nd or 3rd gear there is a studder while accelerating from 1500k to 2k. RPMs will rise to about 2k in 2nd gear and then drop back down to 1800k. Feels like a false shift. Once it slips back down everything is normal again and you can accelerate as hard as needed. Almost feels like the torque converter studders until it starts to lock again. If you keep the RPMs above 2k everything is fine, no studder. If you start out in first it seems to just power through and everything seems fine as rpms are above 2k on the shift to 2nd. This happens in drive, sport, or tiptronic. Anyone ever have this issue? Def seems like it's trans or driveline related, not motor mounts or misfires. Car runs great besides that and is very fast and responsive. No codes or faults in VCDS. Just would like to see if anyone has ever felt this studder In their zf8 at low rpms only and what the issue is?

Originally Posted by PHGARAGE.dk

Did you have the transmission serviced? If yes, and the fault is still there its either the lock up selenoid in the valve body or the toque converter that is toast?
Hope this will help guide in the right direction

Originally Posted by DanTheC7Man

Just wanted to add some info to this thread based on my experience so far. I have the exact same issue as described in the original post. My car now has 146k miles and the transmission has had that 2nd gear slip since I got it around 120k miles. I found no history of a transmission fluid change, so that's the first thing I did but it didn't seem to change anything. I also bought and installed the transmission and drivetrain mount inserts from Eurocode, but that also didn't solve the issue.

There are 2 things I still want to try at this point, which I haven't done yet. First, I want to do the adaptation but haven't gotten around to it, and also not sure how to do it yet. I'll eventually look it up, but if anyone knows how to perform the adaptation of the ZF8 or can send a link about it, I'd appreciate it. I'd prefer doing it in ODB11 if possible, but I also have VCDS if required. In addition, I also bought the "zip kit" from Sonnax that replaces some parts in the valve body that tend to wear out over time and cause fluid pressure loss.

Originally Posted by MyDimeIsUp

Following. I've had this in both my old tranny as well as my new one. My old one had about 113k on the clock, no history of fluid changes at all. Once I was tuned on 034 Stage 1 ECU and TCU and would launch control/AMAX, it would shift from 1st to 2nd, and then once I reached red line it wouldn't shift into 3rd until I let off the gas. I swapped in a tranny from a 62k-mile A7 (right at that fluid change sweet spot). Once we had the 62k mile tranny in, we swapped my TCU from the old valve body to the new one to avoid component protection coding, put a new filter in, and actually pumped just over 6qts (probably since all the fluid had drained out of the torque converter and other nooks and crannies of the tranny).

I've had no issues with launch control since, but I still have that exact same problem with stop & go, along with accelerating slowly from a stop. I was able to log with OBDeleven and the torque converter is slipping for a long time, at which point the TC locks up and the revs will drop from 2k to 1,800 RPM. If I'm in manual mode and do a rolling stop slowly, I can sometimes even shift from 2nd to 3rd while the TC is still slipping, and the RPMS will drop very little during the shift until the TC locks up again. It does this both stock as well as on my 034 tune, and with my old tranny as well as my new one.

I also have that exact same issue with accelerating slowly from a stop and have logged with OBDeleven and 034 when the TC decides to lock up almost immediately after accelerating. When shifting from 1st to 2nd not in manual mode, it feels like power is cut for a good 3/4 second (and feels almost like a manual transmission with the 3/4 delay between engagement of the next gear). What I found from data is that the engine retards timing between the shift so that explains the loss of power, but why is it taking 3/4 a second of timing retardation until 2nd gear actually engages. I'll have to record a video and save the data log. If I am in manual mode and do normal acceleration and shift myself when the TC locks up nicely, the gear change is much much faster, and doesn't feel like a little man is inside my transmission shifting slowly. Under medium acceleration, the TC sometimes lockups up quickly, other times I get that 2k to 1,800 RPM drop. When it locks up nicely, it is pretty snappy. Under hard acceleration the TC locks up almost immediately and gear changes are quick.

Really weird that my 113k tranny as well as my current 62k both have these exact same issues, both stock and 034 TCU tuned. Again I didn't swap the valve body from my 113k mile tranny, just the TCU to avoid component protection.

Originally Posted by DanTheC7Man

I appreciate the explanation about how to do the adaptation! I already have the Sonnax kit, it's just been collecting dust waiting for me to have time and motivation to do it. I think I'll do the adaptation before and after I use the zip kit and see what the difference is. I'll be sure to share my findings once I do.

I'm currently in the middle of engine work (doing timing chain tensioners...), but once that's over I plan to start working on the transmission. Hopefully, I'll have an update by the end of this month.

Originally Posted by Jon8138

I was told the transmission was serviced but I do not have actual records so im going to say no and hopefully get that done soon. Im going to order a trans service kit and drop the pan myself. It does feel like a torque converter or lock up solenoid like you suggest. I don't think the converter is toast but I do think it is not slipping and locking like it should. I had it at a shop a week ago to extract a broken oil cooler bolt from the previous owner and they said the couldn't duplicate it but I can feel and see it drop rpms and rise again right at that 1800k mark every time. It's not as noticeable once warmed up but it's there. I'm hoping to try a trans adaption next weekend. Not sure if this will change anything since flashing the tcu back to stock and stage 1 made no difference. I will hopefully figure this out.

Originally Posted by kronikfumes

Just to let you know, flashing the TCU does not affect the “memory” of the transmission from what I have experienced and been told. Redline changes after a TCU tune and when flooring it you’ll get high RPM shift points, but the “habits” of when it will shifts in normal day to day use do not. It is recommended to do a trans adaption reset after any stage tunes to “retrain” the memory of the TCU/ECU with the increased power/torque of a tune. Once I did the trans adaption reset after getting a TCU tune is when I noticed for a time that the shuddering went away.

I have spent a good while researching this shuddering effect and had no luck finding any good explanations or solution that resolves it long term. Leads me to believe it is just a feature of the transmission. Though with seeing your post, I have picked digging into this topic up again to find more details and I am in contact with ZF about this shuddering. I will report back what I hear.

Originally Posted by Jon8138

Very interesting thank you for the info. We Def seem to have the same "issue" going on. Seems to be a zf8 feature lol. I was going to try and log converter slip and lock myself because that's what it feels like is happening, just not happening well. I have launch control as well but was not sure how to actually use the launch. Do you set the rpm and foot brake from 1st? The only other way I figured was have it in N and have it hold rpms while you drop it into 1st but that seems like a very bad idea. I couldn't find much info on how to use the 034 launch in the zf8, I've set the rpms and they hold, but what configuration do you actually launch in? I didn't want to take a chance when I was alittle concerned about the trans already haha. Thanks again.