03 transmission - Help
 

i have a o3 duramax with 4' silverline exaust and a quadzilla steath 2 tuner and every time i run 135hp more the transmission will lock in 5th gear and stay there. and win i put it back to stock it wount do it.

sounds like your slipping the trans and going into limp mode, are you getting any codes or anything.

i limped my transmission within 5 minutes after i got my quad tuner. and i had set it at 135 when i first got it