Hard shift 6l80e

[jakedewey]

Buddy has a truck that every now and then shifts hard into 2nd. Kind of like a bang. It'll do it then the next time it won't. Just curious for input. Looking to buy the truck if it's nothing major. Going off what I was told, he had it tuned awhile back then it started doing this so he took it to the dealership and they flashed the transmission computer and replaced a silinoid. Said it still did it but never took it back but is going to after the holiday. Could it be with the tune? It was done with efi live. I'd like to have it returned stock then I give it a shot with HPT.

[conekiller01]

My roomate has an 09 crew cab with a stock tune it his will shift with authority into second sometimes but sometimes smooth as butter it's been in and out of the dealership 5 or 6 times now for this and they can't seem to figure anything out either so I'll def be in for an answer if you come up with one!!

[CHEVROLADE]

stupid 6 speeds sometimes there brain goes retarded,its normal....

[bones73]

Just had a l80e swap mine does the same. sometimes it chips the tires.

[jakedewey]

Stock computer? I wonder what it could be.

[graysilverado5.3]

My 09 does the same thing.

[00shortbox]

I've fixed a few of them by changing the fluid rings on the oil pumps, there's a TSB on it. Everyone I've tried has fixed them. This was a 2-3 shift flare though, it'd rev up a couple hundred RPM then bang into 3rd.