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Message: [QUOTE="Tom S, post: 106497, member: 623"] It is interesting you bring this up. I helped Jody (read driver) work on some fresh tuning for the OBS trucks last year. We used a very low mileage OBS truck that was in great shape and really worked on the shifting. We also spent a bunch of time creating tunes designed for mountain driving where the upshift/downshift points are closer. After a couple of days of work I thought it was really dialed in. I have other friends that run those tunes and they really like them and Jody has lots of customers that do as well. I tried those tunes in my truck and guess what? It will not shift at WOT and hits the rev limiter. All of the shift points are off by a bit like 3mph higher. We had come across this before where my truck does not shift at the comanded MPH like trucks normally do. I was wondering what was going on here and if it had to do with my BTS. We tried an experiment and I put one of my spare PCMs in the truck. Magically now those tunes that would not shift at WOT now work just fine. Something in my PCM has a small effect to the shifting to where it does not exactly do what the programming on the chip commands. I am not sure if it is some kind of firmware in the PCM not addressed with a PCM base code or what. My stock PCM is a NAW4 that has been reflashed to a TDE1 code. The test PCM I used was from a 97 truck and was a NAW6 code. Jody was able to address the issue with pretty quickly by lowering the shift points the proper and amount and then driving it a bit but it was really interesting that this happened. I think he said he has only had a couple of cases where this occurred. Maybe your truck is like mine and is the oddball one. It would be easy to blame the tuner if you ordered a chip and this happened but the real issue is with the truck/PCM not acting like the normal. If you have a spare PCM you might want to try this just to see. Tom [/QUOTE]