I got rid of the dreaded 2.73's in my car and had 3.73's installed. I'll start off by saying what a hugh difference they make. The car is a lot more fun to drive. I reprogrammed the PCM with a hypertech unit and it did a good job. My only problem is it was bouncing off the rev limiter with 3/4 to full throttle. I lowered my shift points down 200 rpm on the 1-2 shift and 400 rpm on the 2-3 shift. this helped on partial throttle acceleration, but if I mash the pedal to the floor, it still wants to bounce hard off the limiter. WTF do I need to do to fix this? Also is it normal to have to lower shift points? Most of the time I see everybody raises shift points.

 

ummm...is your tranny slipping?

 

The tranny is not slipping. It shifts just fine except for bouncing off the limiter. I had no problems with the tranny doing this with the 2.73's in it.

 

I had the same problem when i did the 3.42's in my old car. I had to use lt1_edit and lower the shift point mph way down. I think it was the the tranny slipping.

 

First off, what height did you use for the tires. It should be 25.75". If you have something different, set that first then adjust your shift points. Also, what is your rev limiter set at? 6,000 should be fine. It's not your tranny, its just a programming problem. If you have it set at 25.75", 6,000 rev limiter, and shift points at -2, and you still hit the rev limiter, then adjust it to -6 and try that. Then just work your way slowly up. If you need any more help just let me know.

 

Its not your tranny slipping if it shifted fine with the other gears. Mine had the smae problem after I went from 2.73 to 3.73 gears. You need to change the programming to shift sooner under full throttle.

 

I'll have to double check my tire size. I just got new 245/50/16's but I know they vary some in sizes. My rev limiter is still set at 5700 rpm so I will definatly raise that to 6000. Thanks for the help.

 

25.75" should be the correct height for those tires. Let us know if it works or not.

 

I don't know what year your car is, or what revision of HPP you're using, but my car did something very similar when I went from 2.73's to 3.42's. I ended up sending the HPP in for an upgrade and it took care of the problem. Might be worth checking the version and calling Hypertech, I'm sure they've dealt with this before.

 

OK, now i remeber why its doing this. The tranny shifts by MPH not RPM. I have also heard that some of the HPP+ dont work that well at changing shift points for WOT.

So with the new gears you will be running less MPH at more RPM, wich is causing you to hit your revlimiter.

 

Thanks for the responses guys. I have raised my rev limiter to 6000 and lowered my shift points down to 5200 RPM ! None of this has helped. My car is a 94 and I have the Hypertech PP Plus Rev 3.3. I'm contimplating on going to 3.23's and having GM reflash my PCM if I can't get this thing straightened out. I also read where the pcm shifts at MPH and not RPM. This is frustrating . I appreciate the help so far. Does anyone know if this HPP Plus and my 94 can work together, or do I need a different version?

 

I bet its something to do with the Hypercrap programming. It shifted fine with 2.73's? Odds are its the programming thats messing things up. IMO, remove the Hypercrap programming then get programming from www.pcmforless.com.

I've seen too many people rape their cars, making them go slower and slower trying to "tune" their cars with Hypercrap.

 

Hypertech would know. Mine says Version 3.11.1 on it, but it's for a 95, so they could be different revisions for your 94. Give them a call, I sent mine in and they upgraded it for free.

 

Yeah, Hypertech is garbage. I remember when the HPP was the big thing and everybody just had to have one.

Hypertech's nothing more than a $300 fanswitch. I'll be more than happy to sell you mine, if you think that yours isn't working.

 

Z TWENTY-EIGHT---- So, you have the tire height as 25.75", 6,000 rev limiter and shift points set at what? (-6, -3, +2, +5 ???) Is it still hitting the rev limiter or shifting at 5200? If it shifts at 5200, then it will be easy to fix.


Their may be a problem with the hypertech, but I don't think their is. Just call them first thing tomorrow. If you have AIM log on and IM me at "a97blackformula" and I'll help you some more. Just do some testing. Mainly worry about your 1-2 shift first.