Weak 1-2 shift @ WOT

[njj502]

My 05 Sierra really doesn't like the 1-2 shift @ WOT. All other shifts are good (the 2-3 is a real neckbreaker @ WOT) at all throttle positions. It seems as though the shift is either slow or the trans won't properly engage at the 1-2 WOT shift......... Any help would be greatly appreciated.

05 Sierra 5.3L w/ 4L60E

[deezel]

A little more info on your truck would help. Any modifications? Any programming yet? Shift kit?

The stock 1-2 shift is pretty soft - plenty of torque reduction, traction control, etc.

[joecar]

Do this:
a. increase 1-2 shift pressure 5-10% and no more.
b. reduce 1-2 shift time to 0.3-0.4s.
c. reduce 1-2 shift torque reduction 10%.

Go for test drive, and repeat step c. until shift feels firm and positive without jerking or harshness.

[njj502]

Thanks for the reply guys. Torque reduction is totally gone on all upshifts and downshifts. The line pressure has been bumped up and the shift times have been reduced. The truck has a K&N intake kit, headers, true duals, gutted cats, 2 chamber 2 1/2" mufflers, and a EFILive tune.

The truck seems to "pull through" the 1-2 shift @ WOT if that makes any sense. At about 1/2 throttle the 1-2 shift is really firm, not harsh, but at WOT it seems slow or that the trans slips during shift. Reading some of the posts, it seems as though I might need to upgrade the trans with a shift kit and possibly a couple of servos.

Right now I only have a Demo version of EFILive but within the next couple of weeks I should have a full version. If anyone wants to look at my tune, so I don't have to send sreen captures, give me an e-mail address and I'll send it on.

What you all think???

Thanks All!!
Nick