[CME86]

Hello,

I just got caught up to the thread, I have a 2017 Acadia Denali and it has about 107k miles on it, bought it in 2019 with around 50k miles. Full tranny flush and diff and transfer case fluid changes at 70k miles.

It has never done this slip/flare once… Until a few months ago.

The last 2-3 years our city has went and replaced a bunch of 4-way intersections with round-a-bouts. This problem started within months of the first round-a-bout being opened which was part of my wife’s daily drive. And now there are 4 more opened and it has gotten a ton more noticeable.

Can round-a-bouts be the doom to the programming?

Lots of long sustained left hand curves at 10-20mph where a 3-2-1 shift or 3-2 shift is common going in to the round-a-bout and an 1-2-3 shift or 2-3 shift happens while cornering. Having to do double 180* of the round-a-bout twice every morning and every afternoon (drop/pick up son from school).

How does the Tranny learn over time, and how does it change its programming over time?

If you return the programming to brand new or replace your tranny or any internal components that won’t fix the problem if you still have round-a-bouts on your daily drive. It’s going to notice the frequent round-a-bouts and program that slip/flare for the 2-3, 3-2 shift, that’s what it’s programmed to do…

Love this Acadia, but can’t stand this slip/flare… She is so far off warranty I don’t care about programming it and GM finding out, but would pushing higher shift pressures on the 2-3 and 3-2 shifts make her stop free wheeling

Sounds like more than a few have mentioned round-a-bouts being a common item in their drives…

Haven’t driven around since I read this but will drive her around tomorrow and see if I can notice anything in particular.

 

[Grantv]

...Full tranny flush and diff and transfer case fluid changes at 70k miles.
Lots of long sustained left hand curves at 10-20mph where a 3-2-1 shift or 3-2 shift is common going in to the round-a-bout and an 1-2-3 shift or 2-3 shift happens while cornering. Having to do double 180* of the round-a-bout twice every morning and every afternoon (drop/pick up son from school).

I've mentioned a few times that my '19 was far more pronounced on long sweeping left hand turns, particularly if under acceleration (not noticeable downhill).
There's a 6-lane slightly uphill road I turn left onto once every few months, it was easy to repeat on this road.
My 99% belief is it's in the programming, and I intended to eventually have it tuned.
I traded my '19 in on my '23 though, the 9 speed is great.

 

[bxd20]

2018 owner here who has had the 2-3 flare for years. Sometimes changing fluid seems to help for a while but it does come back.

I wanted to say that I began looking into HP Tuners but according to their website they don’t support the second gen Acadia.

If anyone here has a successful experience getting a transmission tune for our 6T70, please do share who did it, what software, cost etc.

It’s not bad enough that I’m going to trade it, but it’s irritating.

Only other data point I’d like to mention is that mine is AWD with tow package, and just recently i started driving in tow mode. So far it has not flared in tow mode. Will keep testing this theory. Shift points are higher in tow mode, so maybe that pulls the RPMs out of the “danger zone”.

 

[Grantv]

Only other data point I’d like to mention is that mine is AWD with tow package, and just recently i started driving in tow mode. So far it has not flared in tow mode. Will keep testing this theory. Shift points are higher in tow mode, so maybe that pulls the RPMs out of the “danger zone”.

IIRC mine was better or non-existent in sport mode (no tow package). I would have left it permanently in this but GMC chose to switch it back to 2WD every start.
I had my dealer flash it a couple times, both times it seemed better at first.
Both of these lead me to believe it's programming. That and after 4 years it didn't get worse. A failing tranny would.
Have you considered a performance shop for the tune?

 

[JayTee2019]

I also noticed when we had our FWD 2019 (no tow package) for just short of 5 years, that if placed in Sport Mode as @Grantv mentioned, it did not seem to do the 2-3 flare. Or at least as much.
I remember reading some placed the shift lever into Drive Select "6" upon starting and said it did not seem to do it as much . . . IIRC.

What irritated me is the 2-3 shift flare would be non existent many times when I drove and other times it would do it often on many drives. In the 5 years we owned it, it never got worse, but due to not driving it as much during 2020 and 2021 we had low miles on it.
By 2024, we happened upon a nicely equipped Acadia SLT with the loaded packages and AWD.