2012 GMC Sierra Hard Shifting

[CJM8515]

Have a 2012 5.3L 6 speed GMC Sierra 4x4.

So Im at a loss to whats causing very hard shifting at partial to wide open throttle. I did the trans firm shift tune, and turned off torque management at the same time. Truck shifted VERY hard at WOT and somewhat harder at partial throttle. I drive pretty hard so this isnt good.

Googled a bit and found people saying the same thing, turned down firmness to -5 for partial shift and -3 for WOT for normal shifting. It helped, but at WOT its still a bit much and makes the truck slam into gear almost, specially from 2-3rd shifts.

Should I turn back on torque management? Remove the firm shift tune? Im sorta confused as there are no real instructions for this tuner.

Thanks in advance.

[06MonteSS]

turn torque management back on..

lower shift pressure more..

get a custom tune done - www.diablewtune.com

there's a table in the ECM/engine side of the tuning that controls timing during a shift - the diablo tunes have that table jacked up high, which causes the hard shifting... only way to fix that correctly is via a custom tune...

[CJM8515]

So custom tune is what really needs to be done huh? For now, Ill turn the torque management back on and see how it goes first.

Thank you for your help.

[hoorsec]

my truck shifts much better on hard shift, the firm is just to bouncy kinda I guess is how I would describe it, try the hard and play with that??

[CJM8515]

my truck shifts much better on hard shift, the firm is just to bouncy kinda I guess is how I would describe it, try the hard and play with that??

Ill have to look into that and see what happens. Is that with torque management on or off?

[hoorsec]

my truck shifts much better on hard shift, the firm is just to bouncy kinda I guess is how I would describe it, try the hard and play with that??

Ill have to look into that and see what happens. Is that with torque management on or off?

always off..lol..

[CJM8515]

Thanks.

[CJM8515]

Still working on this for now. Turned of torque management and the truck is pitiful. It just doesnt accelerate well. I tried to pull out rather quick from a side street and it felt like I was driving a 6 cylinder.

Maybe turn off firm shift and turn back on torque management? This sucks..

About the only positive is the truck doesnt slam into 1-2 and 3-4 now.

Guess Ill be doing a custom tune sooner or later. For now IDK wtf to do to at least get some power.