4L80 Swap , will not move in 1st gear
07-21-2016, 05:58 AM
#1
4L80 Swap , will not move in 1st gear Need some input from you guys, I'm a TH400 guy myself but I just finished up a turbo 6L/4L80 4WD swap in a customers Tahoe.
Fresh rebuilt 80e w/transgo kit
Basic 2500 stall converter
60 to 80 patch harness / ran speed sensor harness to pcm
PCM from 6L/80E Truck. No Trans fault codes
Truck drives completely normal except 1st.
If you put in 2nd and take off can shift into D, works as intended.
If you put in D, takes off in 2nd, shifts into drive, and shifts into over drive, works as intended.
Cruising down the road in overdrive, stomp the gas, downshifts as intended.
Say you're going 10mph in 2nd and downshift it into 1st, its like applying the brakes, the truck will slow down (not violently) and come to a complete stop.
If you're sitting still and put it in 1st, can mash the gas, and the best comparison I can give is it feels like you're on a transbrake, it will go up to about 2500rpm(converter stall speed) and just build boost but not really go any higher.
Anything you guys can think of me to check?
Thanks!
Fresh rebuilt 80e w/transgo kit
Basic 2500 stall converter
60 to 80 patch harness / ran speed sensor harness to pcm
PCM from 6L/80E Truck. No Trans fault codes
Truck drives completely normal except 1st.
If you put in 2nd and take off can shift into D, works as intended.
If you put in D, takes off in 2nd, shifts into drive, and shifts into over drive, works as intended.
Cruising down the road in overdrive, stomp the gas, downshifts as intended.
Say you're going 10mph in 2nd and downshift it into 1st, its like applying the brakes, the truck will slow down (not violently) and come to a complete stop.
If you're sitting still and put it in 1st, can mash the gas, and the best comparison I can give is it feels like you're on a transbrake, it will go up to about 2500rpm(converter stall speed) and just build boost but not really go any higher.
Anything you guys can think of me to check?
Thanks!
07-23-2016, 08:53 AM
#2
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I'm assuming you had the valve body off to do the shift kit. Double check the bolts, it sounds like you might have one of the longer bolts in the wrong spot. If this is the case then the end of the bolt could be hitting the drum inside binding it up. Just an idea, I hope you get it figured it out.
Archie
Archie