[taylorforschool@gmail.com]

I have had my 2018 ZL1 1 owner since January at 12k miles. I have since put 2k miles of lightly spirited back roads and road trips. The entire time I’ve had the car it always shifted smooth as butter every gear no matter the RPMs. Suddenly as of about 2 days ago, it is shifting roughly during low RPM/cruising speeds, and only while left in automatic mode. Manual shift causes no issues, and neither does WOT or aggressive driving. I’m thinking a trans tune issues or maybe needs a flush? I am at a loss as to what to do because I know it I take it to the dealer they will just tell me nothing is wrong. Am I just paranoid

[Vigilante375]

Is it the 3 to 4 shift? That's the gear change that all A10s have issues with while just normally driving around.

I've got nearly 30k on my 2018 (bought new in 2018) and many track days. That's the only gear change that gives me any issues while just driving around normally.

And actually the 3 to 4 shift in manual mode is rough no matter if you're 1% throttle or WOT. But if you put the car back into D after going WOT, it shifts fine.

[taylorforschool@gmail.com]

Yeah it’s definitely the 3-4 I almost felt like one of the higher gears was even a little jerky at low RPMs like even my girl noticing.. but any real driving with serious input the jerking wasn’t as noticeable. I know it sounds odd.. but it was overall very well pinpointed to to the 3-4 shift and possibly the 7-8. It was like the trans couldn’t decide what gear it wanted and paused and even raised rpm by 50-100 right before the RPM drop of the gear change. which was odd and didn’t happen in any other gear or situation.

[Gunkk]

The 3-4 shift is non-optimal.

What I feel is the #4 clutch close too hard before the #3 has completely let go, and it bucks the car. Because clutch closure rate is torque & throttle position dependent, driving style matters here. I find it most severe when the trans is cold and I'm light-moderate on the throttle, upshifting above 2k rpm.

[SATINSTEEL1LE]

Reset the adaptives. Maybe its just pissed off for whatever reason. Pull the battery cable and leave it off for a few hours. That should reset all the ECM and TCM adaptives and should let the car relearn your driving habits.

[d15b7]

What SatinSteel said ^

This is not purely GM related, but my Nissan Titan XD Cummins w/6 speed Aisin has some sort of ‘learns how you drive and adapts the shifting to it’ system too. I bought it brand new and have always maintained it by the ‘harsh use’ book (changing the trans and rear end and front end and transfer case often). It always shifted great (very firm but fine). Then a couple years after buying it, it got a recall notice for a reflash (emissions related not performance related). I dropped it off at the dealership, and they reflsheed it. And then they road tested it for about 15 miles. It was all written down on the receipt. Well, the next day I noticed it was having difficulty shifting smoothly between second and third and sometimes third and fourth gear. And it would especially shift very rough and slam into gear when trying to downshift between fourth and third. It had never done any of this before. I believe what happened was when they re-flashed the computers, and then took it out for a road test, that the technician must’ve driven it very roughly or poorly in some manner, and the adaptive transmission learning was confused. I belong to a message board, and that was the general consensus on what the issue was, as this exact same thing had happened to other folks. I was very curious, and as the vehicle was under a full warranty also, I wasn’t too concerned about a failure costing me any money. So for the next two or 3000 miles I drove the truck the way I normally do, which I think is the proper way to drive a big heavy duty diesel truck, meaning I wasn’t jerking it around or slamming the throttle down or any other odd behavior. Over a period of about 2 to 3 months it gradually got better and better and better. It took a long time for it to relearn itself, but now several years later, it shifts perfectly. I might even say it shifts better than it ever did. It was a gradual learning curve at least for the Nissan, but it did improve.

I would agree with the above that you might try resetting your adaptive learning, and then teach it how to drive again. I don’t think I would be too concerned if I were you either about things. Good luck! I hope that helps.

[Vigilante375]

It's well known that the 3-4 and 4-3 shift in the A10 for the ZL1 is rough in a normal driving situation. Having the car "re-learn" your driving habit's isn't going to fix the issue.

Not matter if you drive like Ms. Daisy or Brian O'Conner, the A10 has the rough 3-4 or 4-3 shift.

You can try disconnecting the battery but don't have your hopes set high in it fixing the issue.

I'm not sure about the 7-8 shift though. The 3-4/4-3 is the only one I know everyone talks about.

[taylorforschool@gmail.com]

Thank you everybody for your he reassurance and knowledgeable options, they are very helpful. I will be trying the battery pull just for my own observations, and will report back.

[taylorforschool@gmail.com]

All of this would not be as important to me as it is now that my current daily driver.. Dodge 1500 with 188k on the clock has a rod knocking sound that just started.. so now my worst nightmare came true and the Z is now the daily until I find a reasonable way out of the mess that is owning a clean turd everyone wants too much money to repolish

[taylorforschool@gmail.com]

So the issue is still persistently happening at approx 58-60mph in what I’m presuming is 8-10th gear under light casual driving. Typically it seems like it’s happening after a short period of accelerations when the TCM is deciding to chill back the RPMs in each gear. Needless to say I’m convinced it’s a GM problem at this point. I’ll pay for fluid flushes if I have to because I know they won’t cover it otherwise

[Vigilante375]

Light casual diving, that's a 9 to 10 shift. I don't ever recall my car have this issue or anyone else on here.

Since you have PDR, record what is going on and post it so we can see what you're seeing. I think the sport overlay with be good enough.

[KingLT1]

Trans tune helps.

[taylorforschool@gmail.com]

Originally Posted by KingLT1

Trans tune helps.

I would love tune my car but given all of the potential issues with this platform.. there aren’t a ton but a few expensive ones. I’d rather wait out the rest of my manufacturers, and my extended coverage if possible. Not in the financial position to fully push this car the way I want to just yet

[taylorforschool@gmail.com]

Originally Posted by Vigilante375

Light casual diving, that's a 9 to 10 shift. I don't ever recall my car have this issue or anyone else on here.

Since you have PDR, record what is going on and post it so we can see what you're seeing. I think the sport overlay with be good enough.

Even my gf notices it.. but I’m sure somehow a GM mechanic couldn’t be convinced. You would only notice it on PDR if you watched the revs.. that’s the dead giveaway.. instead of them dropping as they do on any normal shift it’s like there’s a compression build up and it actually stalls the revs and then shoots then up about 100 or so RPM and THEN it shifts. I’ve never used my PDR before so that’s another thing. GM is really good at sticking you between a rock and a hard place