Write-Up: Performance Shift Knob

If this is not already here somewhere, I'll be making a pretty detailed writeup on installing a regal GS or similarly functional shift knob (to be able to use the performance shift function)

http://www.rivman.com/perfshift.htm

Above is a link to Rivman aka Rob's page that basically has the fundamentals of the writeup.

This writeup may be a lot shorter than I thought. I just went out and checked my PCM harnesses. Rivman's writeup states that pin 21 on the clear connector is the one that renders perf shift on (when you ground it). On my '97 riv PCM, pin 21 is already occupied on both the clear and blue connectors. Anyone know if my year will use a different pin for that or if the PCM doesn't have any pin for it or what? The '97 GTP's had it and I can see the complete perf shift tables on my factory tune.

I had not considered that Rivman was actually using a 200X GTP PCM in his riv. Any ideas? I'm going to ask him about it next time I catch him on aim but if anyone knows what pin it would be on my PCM, post!

For us dummys, could you explain what perf shift is and what it does.

Rickw wrote:

For us dummys, could you explain what perf shift is and what it does.

Performance shift or perf shift is just a funtion that most GTP's and Regal GS's have from factory that renders a more aggressive shift behavior. The button that enables it is located on the side of the shift knob used in these cars.

Physically, what this button does is short pin 21 on the clear connector of the PCM to a ground (some say with a 348ohm resistance) What that does is tell the PCM to switch to it's alternate (performance) shift tables. This funtion affects shift quickness, line pressure, shift points, etc.

There is technically nothing that this perf shift function will enable you to do, performance-wise, that you can't do with reprogramming but it does enable you to switch between two completely different transmission settings on the fly.

On factory programming, the perf shift tables aren't drastically different than the normal table but again, you can manipulate it how you wish with programming.

Thanks for the explanation.
When you find out if we can utilize this with our PCM's or not, will you please post that info.

I have always thought it would be cool to wire a relay to the Trac Control button that would activate Perf Shift when TC is turned off. I know it could be done, and planned on it for a while until I got a tuner. I could then turn Perf Shift on or off by throttle application.

ok question for DHP or Tech2 users: Can we confirm that a 97 (and other years) riviera uses the perf shift program or normal shift program?

I looked in my 1997 factory service manual and it shows that pin 21 goes to ground. If the PCM exclusively uses the perf shift tables, then it might make sense that I can cut and switch that wire to render perf shift on and off.

If this pin is actually for perfshift on a 97 riv pcm, I would take a stab and say that the 97 doesn't need the resistor(s) like some cars do, since it's already directly grounded as it is.

turtleman, any luck with this?

curious riv wrote:

turtleman, any luck with this?

not really

I did a crude test to figure out which shift tables my factory program uses and I'm pretty certain it's the normal tables, so that doesn't really support the theory that pin 21 on my PCM is for perfshift like all the rest. I really doubt that the relationship between the circuit status and the table used would be inverted on my PCM.

I don't really know what else to try at the moment and i'm not desperate or convinced enough to cut that wire just yet so unless I get some new information on this, the project's on hold.

Worst case, this button could be used as a factory-looking arm switch for nitrous or anything that I might need a switch for in the future.

I'm waiting to catch Rob on aim again to see if he has any further knowledge on this.

I will add to this that a perf shift knob is really unnecessary if you have a DHP or HPTuners - just redo the shift tables so that light throttle involves stock settings and heavier throttle uses higher pressures and crisper shifts etc... and your 'perf shift' comes on when you step on the gas.

That said, supposedly the '98-'02 PCM is supposed to be capable of this mod you describe, whereas the '97 PCM might not be due to hardware limitations.

A few years ago I asked Rob the same question about adding a performance shift button to a 98riv. I can't remember his correct response, but I think he said something about you needed an aftermarket pcm (this was back before the powertuner, etc.) for the performance shift to work. Maybe someone can confirm this, but does the stock pcm file have a performance shift table? I thought it didn't, but I can't remember for sure.

The stock file definitely has the perf shift tables and they are also populated with the same stuff.

Derek, I know for sure that the '97 GTP's had perfshift.
If my PCM is wired differently for some reason, I'm just gonna give it up. I would like to have a 98-99 PCM but I'm not going through that kind of hassel.

Yeah, the stock PCM definitely has performance shift tables, they just never get touched.

If you want to work on your shift tables, let me know and I'll be happy to help you improve them...

I guess I remembered it wrong. I wonder why they never used them?

They pretty much made the same PCM or very similar for all the 3800s, some could handle slight hardware option changes, then for '98 -'02 3800s they should all be the same hardware-wise. Perf shift tables were not used on cars where they didn't see the need, i.e. Pontiac GTP had a Perf Shift button some years, Buicks didn't. (did some regals?)

deekster_caddy wrote:

They pretty much made the same PCM or very similar for all the 3800s, some could handle slight hardware option changes, then for '98 -'02 3800s they should all be the same hardware-wise. Perf shift tables were not used on cars where they didn't see the need, i.e. Pontiac GTP had a Perf Shift button some years, Buicks didn't. (did some regals?)

I think there were some years where the Regals had a performance shift button.

Paul cleared this up for me.
For the 1997 PCM, grand prix, riv, etc, it's pin33 on the clear connector. Just jump that baby to ground with a switch and perfshift is enabled.

Hey, thats pretty cool, is that only 97? or other years too? (like 98?)

Karma wrote:

Hey, thats pretty cool, is that only 97? or other years too? (like 98?)

The 97 is the odd one. They all have the perf shift program though - but it's a different pin on the PCM - see earlier in the thread for the 98+ one.

98riv wrote:

deekster_caddy wrote:

They pretty much made the same PCM or very similar for all the 3800s, some could handle slight hardware option changes, then for '98 -'02 3800s they should all be the same hardware-wise. Perf shift tables were not used on cars where they didn't see the need, i.e. Pontiac GTP had a Perf Shift button some years, Buicks didn't. (did some regals?)

I think there were some years where the Regals had a performance shift button.

There most certainly were regal gs's with a perf shift button. They have a button on the shifter just like the grand prix's - different shifter of course
It looks like...

Can this be done on a 95? Considering its the oddball and has a completely different pcm I'm guessing no but it never hurts to ask.

turtleman wrote:

Karma wrote:

Hey, thats pretty cool, is that only 97? or other years too? (like 98?)

The 97 is the odd one. They all have the perf shift program though - but it's a different pin on the PCM - see earlier in the thread for the 98+ one.

Is there any data around for the 96?

Turtleman,
I noticed a red wire coming from your Perf-Shift button.
Is that wire safe from being chafed by the shifter itself.?

And, did you get it hooked up to your PCM and how does the car respond with that table activated.?

Rickw wrote:

Turtleman,
I noticed a red wire coming from your Perf-Shift button.
Is that wire safe from being chafed by the shifter itself.?

And, did you get it hooked up to your PCM and how does the car respond with that table activated.?

When I got that shifter and was testing fitment, I didn't know of the correct wire for my 97. It was at that point I looked at pin21 on my PCM harness and saw that it was already occupied by something else and figured I just didn't have it on mine. I just found out about the alternate pin location when I saw PRJ Paul recently. So I can't answer your question, yet, about how it responds.
For temporary purposes (mainly to make sure it does work) I'm going to use a toggle switch and hook it up so I'll be able to confirm that it does work.

Our factory tune does have more performance oriented settings in the perf tables so I'd reckon it should be just like hitting the perf button in a stock GTP. Of course you can change both normal and perf-shift tables if you have a tuner so you can set it up how ever you want.

As for the knob itsself, the wire comes out the bottom of the knob right next to where the shifter shaft goes into it so there's no way to hide it without some sort of boot solution. The regal GS has a big leather boot that fits to the bottom plate and covers it all up. There's enough room where the shifter shaft goes through the plate (where the plastic shutters are) that if you retain the wire decently well underneath, it shouldn't chafe on anything.

I've tried a couple different things for hiding the wire and I didn't come up with anything I was satisfied with so I'm probably not going to use the shifter. I have a whole new plan for where that button will go.

I got the wiring added to the PCM harness with a new pin with just a simple toggle switch for now. I still need to edit my PCM code to enable perfshift, it turns out. I'm not sure if it's a year thing or a riviera thing but I'm trying to get with someone close who's got a DHP. I cannot edit the code with my HPtuners nor can I flash any edited bin files. FAIL

oh, the lines that need to be edited in the code are these:
Transmission/Shift Switch/Shift_Switch_Type = 1
Transmission/Shift Switch/Discrete_Switch_Debounce_Time = 25
(This is what they need to be for it to work.)