Just to clear up, the PCM uses BOTH mph and rpm to shift the car...you have to meet both tables in order for it to shift. In other words, for it to shift to 2nd @ 5200rpms you car has to be ABOVE the mph for whatever %your tps is at. So basically, just lower your MPH way down in order to meet BOTH requirements.

Also, it could very well be your tranny....I did the EXACT same thing you did, went from 2.73's to 3.73's in my 94 and had the PCM sent off to PCMFORLESS to reprogram it, and I was hitting the rev limiter on the 203 shift hard, sent it back, had him lower the shift point another 500rpms, still, not luck...a little better, but not good enough.

Finally, I put heads/cam in my car, 2nd WOT run, 2-3 at WOT goes bye-bye....so, dont rule it out all together. My car shifted fine with 2.73's before I switched.

Good luck.

 

Tire height is at 25.75", 6000 rpm rev limiter, (1-2 shift is -4), (2-3 is at -5). The 1-2 shift does not bounce off the limiter so far, but I'm afraid to hammer down to much on it in case it is my tranny. The 2-3 could be lowered still. Also I'm noticing that my 1-2 shift needs to climb up in the MPH-RPM's with half throttle acceleration. It is definatly not slipping. It acts like it needs (searching) the right MPH RPM combo to shift. When the tranny shifts, it is quick and hard (Trans-Go 2 washers), I have the fluid and filter changed every 15000 - 20000 miles in the tranny as well. I've never had burnt fluid and the tranny after inspection is always given the 2 thumbs up. I don't drag race my car or beat it, but I don't baby it either. I think I'm going to get some custom tuning and see if that helps. I'm also going to have my tranny inspected again, it has about 7000 miles on it since the last fluid change. I'll probably toss the Hypertech PP+ in the toilet, throw some TP on it, and send it on its way to join the rest of the crap. I REALLY have a feeling that my problem is in the tuning, but I also realize that I could be in for a tranny rebuild . 1982z28with18s I don't have AIM.

 

Ok, I know you don't wanna abuse your tranny but you need a WOT run with a 1-2 shift. Then watch the tach as it shifts and let me know what rpm it shifts at with the setting -4. Lets just work on the 1-2 shift first. Once I know what rpm it shifts at then I can help you more. Also, I don't have my hypercrap book here and its at home burried somewhere. So can you let me know with 3.73's, what changing 1mph will change in rpms. Such as 1mph is 150 rpms or something like that. Get me this information and I can help you out some more. Since your not hitting the rev limiter I think we can fix it with the hypertech. After we get the 1-2 shift fixed, we can work on the 2-3 shift.