2023 duramax 2500 shift flare

[Deadstockpomp]

Had my valve body replaced, have around 3k miles on the new one and sometimes when cold or when letting the truck sit for a while the 3-4 or 5-6 shift not sure which one will flare. The Rpm’s will raise before the shift is complete. Then it never happens again during the entire drive cycle. Can’t remember if the original one did it or not. Ideas ?

[waltman]

Mine does the same when cold, usually once and then it stops. The transmission in my truck hasn't been touched so I'm thinking it's normal. I had a 2019 f150 before this one and it would do the exact same thing.

[BuckWallace]

I have a 2024 L8T gasser with the 10 speed and mine does the exact same thing under the same conditions.

[Deadstockpomp]

Also I feel like that 3rd shift generally in tow mode or not once warmed or whenever is a tad slower than the other shifts when driving. The rpm will start to decrease a little before the shift. It’s more drawn out like it settles into that gear?

Edited April 18, 2025 by Deadstockpomp