Hard shifting during down grades

[14cris]

I have a 2014 slt 4x4 sierra only engine mods is a cold air intake

Truck has 83k miles

Recently I’ve noticed that if im in a downhill grade and im coasting slow lets say about 30 mph going to 20mph it shifts HARD!

And ive noticed that if give it gas once the downhill grade is over it’ll make a clunk noise like if it was in a high gear and needed to shift a long time ago

 

I have an 04 mustang gt with 4.10s in the rear end and when it downshifts it feels exactly like this kind of throws you to the front dash, but on this truck it only does it sometimes, i do not take it to the dealership since i do my own services on all my cars that do not have warranty left, but I’ve read somewhere that there was a system program available through gm to fix some tranny issues on the 6spd? Or just 8spd?

 

 

 

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[1SLOW1500]

Possibly a hill assist? Or a combo of torque management and deco. You could try to.manualy down shift and se how it acts or disable hill assist. 

[Mozzer]

Crap programming, mine has been like this from new, feels like the torque converter doesn't unlock during down shifts at light throttle. Big clunk through the drive train.

Still trying to find a solution before warranty runs out in June. Dealer says 'normal'.


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[1SLOW1500]

We it is normal. I hate it but with DOD, DECO, and stock shifts that is the way it is. As stated it can all be programed out or you can try tow mod and see if it goes away, then you would know it is DOD. 

 

[14cris]

So do i need a tuner basically to fix the shifting pattern?


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[Mozzer]

Good question, I don't know if tuners adjust the torque converter action or just shift points & pressure.

For me driving in tow / haul or M5 makes no difference to the banging issues.


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[14cris]

Good question, I don't know if tuners adjust the torque converter action or just shift points & pressure.

For me driving in tow / haul or M5 makes no difference to the banging issues.


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I just feel that if someone pays 40k for a truck it shouldnt be “normal” for the drivetrain to be banging and or not knowing what gear it wants to be in, i could be driving and if i want to pass someone or let off the pedal it’ll bang sometimes, my dads 18’ model sierra does this too and so does my brother inlaws 14’ sierra as well


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