I've got a 2007 stock 4L60E. 62k miles. Just installed a KB racing turbo kit and 42 lb injectors. Starting to do the MAF tuning with idle and partial throttle but out of the blue my transmission started slamming gears (1-2). Even at part throttle or while getting into the throttle its hitting really hard. I have not really gone over 4K rpm and no WOT yet!

In addition to that, when I come to a stop light after cruising at around 40-50 after about 5 seconds (while completely stopped) it feels like I am getting rear ended. Seems like its shifting back down to 1st?

I've been searching here like crazy and all I can come up with is possible a TPS sensor being the cause? Any thoughts?

 

Not sure what tuner your using but seems like I remember in EFIlive a MAF patch that you can enable to help when tuning the MAF.

 

I'm using HP Tuners. I did have an issue last time I tried to write the tune to the PCM where I got an error indicating my TCM would not respond. I had to install the HP Tuners latest code to get it flash the tune properly. Wonder if that is related?

 

Brought the truck to a transmission shop and had a full flush/filter/fluid change done. The mechanic said the pan was clean, no metal, etc and also there were no codes when he scanned it.

No luck...still getting some hard 1-2 shifts.

Will replace the DBW Throttle body next and see what happens.

edit: I should also add that this only happens when its fully warmed up. When the truck is cold it shifts as smooth as silk.