OK, just dropped a new custom tune into my friends truck.
the truck is an 02 silverado rcsb 5.3

Now, the SES light came on. Crank relearn I pressume. Heres the weird part. At 1/2 - WOT the truck will shift from 1-2 fine, then ater the rpm drop the rpms shoot back up (like it down shifts) and the engine revs out but the tranny does not seem to engage. It just seems to slip through the gear. At the top of the gear it finally engages and take off.

WTF???

can this have anything to do with TQ management?
Or some kind of affect from the SES light (safe mode?)

Any help is appreciated.

 

Have the tune checked something is not right if it does that.

 

WE put the stock PCM back in and now the problem is occuring again. It did not do this before on the stock tune. I am thinking it threw a code that has to be cleared, then it will run right again? Anyone verify this logic?

 

If it was OK on the original PCM/Tune and you put a aftermarket tune and a PCM in the truck and the trans started doing stupid things and you put the stock PCM back in it it should go right back to the way it was originaly, One of two things happened either your new PCM/Tune hurt your tranny or it was just a fluke and it just happened to crap out on you at the same time. I would put the stock PCM/Tune back in it and go see a trans guy. I have seen to much line pressure stick a servo before so maybe it is just something stupid. Good Luck!

 

I was afraid of that. Also, to add to the weird things. Once it hits 6000 rpms, it acts as if it is hitting a rev limiter. I know, for a fact, the tune was not very aggressive on the shifting part. Freaking bizarre.

 

Sounds like his tranny is slipping to me.