dubwise

Jamie, do you have the capability to datalog the issue?

Sounds like you have it narrowed down, as you know the issue is not a mechanical problem now. Some things I would check would be the tune as you stated, the TPS, and especially the pinouts of the harness/PCM.

Also, what year truck is the trans out of? IIRC, there was a change in the 4L80E around 94-95. You may want to double check, or maybe someone else here knows -- but can the LS PCM control both a post & pre 94/95 4L80E..?

BigBlock90

iTrader: (4)

Hey Joel, the trans is out of a 99 2500 truck. We been having this issue ever since i went to the LS/turbo/80e swap and we datalogged it sunday at the track and it showed this shift problem. Immediately upon launch it starts to shutter trying to shift gears from 1st to 2nd constantly and then would grab first and blow the tires away and isnt commanded to do so. This actually happens at 4000rpm and ive been reading alot of threads stating that the torque management is what is causing this. We have zero'd those tables, turned them up to very high numbers to no avail. Hooking my manual controller back on cured that issue but sucks now....i liked the idea of launching in drive and letting it shift by itself at the commanded rpm.

Wrecker 426

iTrader: (2)

any word on whats going on mine is acting up also