2015 Silverado 5.3 "Hard Shift" TCM program inconsistant

[Brad_1983]

Just got the i2 for my 2015 Silverado 5.3 and was hoping for a vast improvement over the rather horrible stock transmission programming. I loaded up the 87 octane tune, torque management off, speed limiter off, throttle boost set at +2, 1-2 shift rpm set to 5800, and the hard shift tcm tune. While it is definately an improvement over stock, I wouldn't really say its a "hard" shift. In fact, the only times I can really feel a difference is at part throttle. At WOT, it's just as mushy and slow as stock. I think that's the real issue, the shifts are incredibly slow. Is there any way to make the shifts quicker? There is a considerable lag in my case to the point I can feel myself move forward and then back once it shifts. This is in stark contrast to when I had a superchips programmer on my 2005 dodge. Is this just because it shuts down the throttle to shift? I thought removing torque management would keep the power on and not feel like I'm letting off the gas and then back on it. Can upping the transmission pressure help with this? I left that alone for now. So, I guess my question is, should I adjust my expectations and be happy with the mild improvement over stock or can things be adjusted further to actually reduce the long shift lag still seemingly present?

[Brad_1983]

Since no one from diablo cared to comment... I thought I'd share my experience in the hopes of helping the next person.

I've found that the "throttle boost" feature is more trouble than it's worth. Most, if not all, of the weird transmission behavior has been solved in my case by just not fiddling with the throttle boost and leaving it at zero. Additionally, I've upped my shift pressures across the board (5% part throttle, 8% full throttle) while leaving shift rpm stock on the "hard shift" TCM program. I would say it's a pretty positive difference. The 2-3 shift is noticeably harder than all the others, and the 1-2 is still very soft, but it's much more drivable.

Next step will be to try to move the shift pressures up even more... maybe leaving the 2-3 pressure where it is now and see how that pans out.

Hope this helps someone.

[techntrek]

Good info, thanks.

[DrDan]

I have the same set up as you do...2015, 5.3, 6 speed, 87 tune-hard shift.
I think everything shifts real good...except for the 2-3 shift, it is harder than the rest.
I've been playing around with it but can't seem to make it shift the same as the rest.
Shift pressure up, down, higher rpm, lower...can't seem to get it where I want it.
Maybe it's the transmission itself?
I guess that is some of the fun of having something you can play with on your truck.
It keeps you from getting bored.

[DrDan]

Something else you can do...instead of tuning down the "hard shift" tune,
select the tcm modify stock shift, and tune it UP.

[techntrek]

Doing lots of towing right now, I've noticed the same thing, with the 2-3 shift very hard compared to the 3-4 (and higher shifts) at full throttle.