Stock perf shift question

[shooterc5]

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?

[carnutcass]

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.

[kustomkid54]

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.

[shooterc5]

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

[Odin]

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???

[fuzzydice]

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?

[carnutcass]

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.

[kustomkid54]

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

[BIG-L]

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~

[kustomkid54]

First time this has ever happened. I forgot to say Big-L sent that to me.

[fuzzydice]

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?

[carnutcass]

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.

[93cobra]

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.

[fuzzydice]

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?