Stock perf shift question

Can anyone tell me on a 99 gtp when u put it into perf shift mode does the stock pcm change anything else besides the shift points? I have seen on the after market pcms when put into perf shift mode many things are changed. How does the stock pcm work?

According to Thrasher Engineered Performance.......

As most of you already realize, our transmission (known as a 4T65e) is electronically controlled by the engine / transmission computer (PCM - Powertrain Control Module). Shift points, TCC (Torque Convertor Clutch) lockup, and line pressure are all controlled by the PCM programming. Fortunately, the factory engineers gave us a choice of a normal shift pattern and performance shift mode for slightly firmer shifts and more aggressive shift pattern.

Not sure this helps.

I was told by GM that it raises pressure in trans for a harder shift. BUT as we all know, What the hell do they know.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP001.jpg

lol very good point. I think it just raised the shift points and line pressure slightly

is there a way 2 add this button 2 my gt i have none and im sad! or can i have it set in the pcm???

I was wondering the same thing. I have a 2001 GTP, no sport shift, but it has the indicator in the cluster. Somewhere I read if you ground the green wire that's in the PCM harness, you can engage the sport shift mode. Any info?

Nope.....doesn't work. I have an '02 and tried it. Vehicles that were not equipped from the factory with Performance Shift don't even have a wire in the harness to the appropriate pin.

OK, this is what I found. Cass says it won't work. But this is what I found. http://www.rivman.com/perfshift.htm
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP003.jpg

OK, this is what I found. Cass says it won't work. But this is what I found. http://www.rivman.com/perfshift.htm

Thats if you have an aftermarket PCM, DHP/Intense or GPstore.IIRC you can also just gnd the wire from pin 21 and the PS will be on all the time.

~Larry~

First time this has ever happened. I forgot to say Big-L sent that to me.
http://img.photobucket.com/albums/v425/kustomkid54/1998PontiacGrandPrixGTP004.jpg

So the answer is you need a aftermarket PCM if you want the Perf Shift? What about using a stock GM PCM that was designed to be used on a GP w/ the Perf. Shift option?

Hey kid.......info from the link you included says, "Following these instructions you should be able to add a performance shift switch to any 98-2002 GT/SE or 2001-2002 GTP equipped with a Digital Horsepower PCM."

I know first hand that you cannot simply add the jumper (or ground) wire and have Perf Shift.

IIRC, didn't the '99 GTP come equipped with Perf Shift? If so, a '99 PCM could be used, in conjunction with a jumper or ground wire, to add Perf Shift without having to pony up for an aftermarket PCM. Oh wait....he was trying to add Perf Shift to a GT.......never mind.

I just bought a 200 GTP Daytona Pace Car. It has the perfomance shift. My question is can you engage it at anytime or do you have to come to a stop first. The previous owner told me to come to a stop before engaging. I didn't read anything one way or the other in the owners manual.
You're a bunch of great people in this forum. Thanks for all the info that you share.

Carnuttcass..could I use a '99 GTP PCM on my '01 without affecting/changing any of the defaults that would be part of the '01 PCM?