Im trying to help a friend that is having an issue with the 1-2 shift. The truck shifted fine until he made a pulley change and installed a Yank sc 3000. The truck is 2010 z71 with a 6l80. The truck falls on its face pulling fuel when shiting to 2nd, once it shifts it runs like a raped ape. The truck was tuned at LMR and they are scratching thier heads trying to figure out the problem. Any help would be greatly appreciated!

 

it sounds like what happens to my truck when i manually shift into 1st doing a 40 punch, and then if i hit the rev limiter if falls on its face and takes about 2 seconds to shift into second....is he hitting the rev limiter maybe?? just a thought..

 

The same thought that popped into my head.

 

no he isnt hitting the rev limiter. All of TM is turned off, but it will flat out fall on its face until the shift and then run hard. They had a hard time getting the converter to lockup until a tech for yank lined them out, but then this problem started. LMR is saying it an HP tuner probelm.