I have an 07 4L80E in my jeep and have been experiencing erratic hard shifts. The trans has never been hot and stays between 125/165 when I'm driving.

On some days it performs flawlessly and on others after I've driven a few miles it begins shifting extremely hard from 2/3, 3/4. I haven't been able to establish any pattern so I'm thinking it's a solenoid or sensor going out, but that's just my guess.

It does have an HD2 kit installed but this shifting is basically like it's being hammered I to gear no matter what speed/rpm.

Tuner said be can't find any issues and tranny shop who installed the kit tested the transmission and converter and said it was working as it should. Not sure if they had experienced the hard shifting while they had it.

Besides taking it to another transmission shop, any suggestions?

I've got a speartech harness and its being controlled by the com/hp tuner programming.

 

Put a pressure gauge on it and see if the pressure is staying maxed out.