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I just picked up a used 2017 SLT Acadia with 35k miles and found the 2-3 flare. Never noticed it in the test drive. Oddly enough in my commute there are two left turns on level ground where the flare is very evident and feels to be around 1/2s or so, enough to feel the vehicle to slow. I'd be interested if flashing solves or minimizes the issue.
I tend to believe the flare problem is not entirely transmission software related. In 3 years and 30k miles of owning an '18, I've never experienced a flare issue.

In my mind, I think it is a combination of things, driver style, transmission software and cylinder deactivation software.
Some owners complain about it, but does not seem to be a wide spread issue.
 

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I tend to believe the flare problem is not entirely transmission software related. In 3 years and 30k miles of owning an '18, I've never experienced a flare issue.

In my mind, I think it is a combination of things, driver style, transmission software and cylinder deactivation software...
Agree on driver's style and software. But can't see cylinder deactivation software playing any part. It never flares anywhere near where cylinder deactivation is possibly in play...
 
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In my mind, I think it is a combination of things, driver style, transmission software ...
I'd think road grade and possibly transmission fluid temperature would have something to do with it, too.
 

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I'd think road grade and possibly transmission fluid temperature would have something to do with it, too.
Grade: Mine will only do it under light to medium throttle (so generally no downhill 2-3 shift), generally 2600-2900 RPM. So the grade is generally light. Steeper grade requires more gas/RPM's, and thus less likely to occur. But I can make it happen regardless, just forced lighter throttle/2700RPM shift point.
Temp: It is more so likely when the fluid is warmed up (a couple blocks is enough), but can be cold as well, just not as pronounced. Barely warm or higher temp tranny fluid makes no difference IME thus far.
P.S. I have mentioned before, the street that connects ours to the main roads to get to the highway have speed bumps. So I generally shift 1-2, then 2-3 is somewhat slowed due to the next bump coming. Does that play a part in my BCM learning my driving habits, and thus affecting my 2-3 shifts? I kinda think so.
 

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So I had my '19 in for its last free oil change today (first 4 free). Asked if they would flash the tranny programming again as the 2-3 flare still happens.
Instead of just doing so they tested it while up, and could repeat the flare.
Ordering a new valve body. From what I know though... the valve body might not fix it. I personally feel this is programming.
One thing I will say, it has never got worse over the almost 2 years, just has that flare...
 
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So I had my '19 in for its last free oil change today (first 4 free). Asked if they would flash the tranny programming again as the 2-3 flare still happens.
Instead of just doing so they tested it while up, and could repeat the flare.
Ordering a new valve body. From what I know though... the valve body might not fix it. I personally feel this is programming.
One thing I will say, it has never got worse over the almost 2 years, just has that flare...
Agree on the programming. I'm sure you'll let us know if it makes any difference. It may, initially, if for no other reason the transmission will have to go through "relearn".
But hope it does make a difference for you. . . (y)
 
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Agree on the programming. I'm sure you'll let us know if it makes any difference. It may, initially, if for no other reason the transmission will have to go through "relearn".
But hope it does make a difference for you. . . (y)
They flashed it, felt fine on the short drive home.
Will see more tomorrow. I am going to avoid the usual street out that has speed bumps, making me slow down right before the 2-3. Instead I'm gonna rip it up for a bit. :oops: :D
Not holding my breath on the valve body really changing it.
The tech guy said what I've been thinking... when warranty is up, get a tuner to make things more to my liking.
 
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