Last week I had the chevy dealer do a trans fluid/filter change. Prior to the change the car ran great-etc. I have a custom wait4me tune, TQ management removed, firmer shifts etc. After the fluid change the car shifts smoother, but will only kick down to a lower gear when going slower. B4 it would kick down to 1st if I was going like 30mph. Or at 67 mph I could kick down to 2nd. Could they have reprogrammed the PCM? or forgotten something?

 

fluid can actually affect the tranny alot...check the level...im pretty sure they wouldnt have hooked tech2 up to it and done something