'17 Yukon Denali - trans problem??

[Nick Bernier]

The trans in my 6.2 Denali (with tow pkg, 2WD) has always seemed to have rough shifts. It is not a smooth application of power to the rear wheels. I've had it looked at by GMC 3 times. They've updated the software, replaced the valve body, and now say it shifts normally. I know the throttle is 'fly by wire', but does the trans control any of the throttle movement? It seems that sometimes, the throttle is dropped back to idle momentarily during shifts, mostly the 1-2 and 2-3 shifts. Does this trans "learn" my driving style? If so, can it be reset to re-learn? I have friends with the same vehicle, and theirs seem fine. Anyone else feel like their trans is similar?
Thanks,
Nick

 

[GreyStone]

https://www.tahoeyukonforum.com/threads/transmission-slipping-searching-for-gear-16k-miles.119581/

 

[sealandsky]

Hi Nick - There is an inter-relationship between the ECM and the TCM, however I'm not technical enough to accurately explain all of the nuances of that relationship. Based on your model year I expect that you have the 8-speed transmission which is widely accepted to be somewhere between marginal and horrible (depending on your individual experience). I think the "easy fix" is to trade for a 2018 or newer Denali which has the entirely different 10-speed transmission that so far is pretty darn good.

 

[Nick Bernier]

Hi Nick - There is an inter-relationship between the ECM and the TCM, however I'm not technical enough to accurately explain all of the nuances of that relationship. Based on your model year I expect that you have the 8-speed transmission which is widely accepted to be somewhere between marginal and horrible (depending on your individual experience). I think the "easy fix" is to trade for a 2018 or newer Denali which has the entirely different 10-speed transmission that so far is pretty darn good.

Thanks GreyStone and SeaLandSky. It's not so bad that I want to trade it, or maybe it is. I'm sure we're all pretty picky about how our vehicles perform. It does drive me crazy. At least I'm on the record at the dealer about the problems. Thanks,
Nick

 

[Tiredmechanic23]

These vehicles cut fuel on upshift. I know Blackbear can and typically does kill that feature on their tunes. That fuel cut my be exaggerated by a slow or laggy shift or a slip. I can make it feel like the vehicle has no power then jerks or snatches power back on after the shift and make a rough shift feel worse.

 

[sealandsky]

The trans in my 6.2 Denali (with tow pkg, 2WD) has always seemed to have rough shifts. It is not a smooth application of power to the rear wheels. I've had it looked at by GMC 3 times. They've updated the software, replaced the valve body, and now say it shifts normally. I know the throttle is 'fly by wire', but does the trans control any of the throttle movement? It seems that sometimes, the throttle is dropped back to idle momentarily during shifts, mostly the 1-2 and 2-3 shifts. Does this trans "learn" my driving style? If so, can it be reset to re-learn? I have friends with the same vehicle, and theirs seem fine. Anyone else feel like their trans is similar?
Thanks,
Nick

is the "dropping back to idle" at light power application or full throttle?

 

[Nick Bernier]

These vehicles cut fuel on upshift. I know Blackbear can and typically does kill that feature on their tunes. That fuel cut my be exaggerated by a slow or laggy shift or a slip. I can make it feel like the vehicle has no power then jerks or snatches power back on after the shift and make a rough shift feel worse.

I looked at the Blackbear web site, and it appears they don't have anything for 2017's.

 

[Nick Bernier]

is the "dropping back to idle" at light power application or full throttle?

At light power application. It seems to shift better during more aggressive acceleration.
Thanks,
Nick

 

[Tiredmechanic23]

I looked at the Blackbear web site, and it appears they don't have anything for 2017's.

http://store.blackbearperformance.com/AutoCal-V3-Tuning-System_p_1467.html Just select 2017- 2018 with 6 or 8 speed trans based on what you have. They can absolutely do 2017s Im not sure how to tag someone in a post on here to get their attention but you they do participate on the forums and you can contact them if you would like.

 

[Nick Bernier]

http://store.blackbearperformance.com/AutoCal-V3-Tuning-System_p_1467.html Just select 2017- 2018 with 6 or 8 speed trans based on what you have. They can absolutely do 2017s Im not sure how to tag someone in a post on here to get their attention but you they do participate on the forums and you can contact them if you would like.

THanks. I'll give them a call Monday!
Nick