My PI300

[MarauderMark]

I just got my PI-3000 installed today .and what a big difference!!!i know im into the 12's now ,will post when i can.i used to have this neck snapping shift from 1st to 2nd even at slow speeds well its gone now ,until i get on it.i didnt know the stall speed made that much of a difference glad i had it installed :D :D . now all i got left is the water pump ,rims &tires..Thanks dennis and this site..

[merc]

Are you ready for the track now... :up:

[CRUZTAKER]

It makes a MAJOR difference!

Now make sure you have the EEC lockup parameters adjusted to further enjoy it.

[FiveO]

My PI TC is going in next Wednesday... :D


Going to the track this Friday to get a nice baseline.


Can't wait!!!

[HwyCruiser]

Mark,

Glad to here you're digging the PI! :up:

You're pushing a whole lot more power than I am, but with the PI in my n/a MM the shift firmness is just the opposite.

After the TC install and before DR's new tune with Jerry's TC values, she would "hump" into gear and then lock, then unlock with a little gas, then "hump" and lock again... Now at anything but WOT the TC locks up immediately giving a firm and clean shift and stays locked unless I dig back into it.

At WOT, it seems the TC is left unlocked allowing it to load up through the shift. Its strange to see the RPMs drop right after the 2nd gear shift and then not change all that much while the speed continues to climb almost at the same rate before the shift until the TC stalls (I assume), and then the RPMs start to pull up strong again. Not the dreaded hesitation, but something completely different. Jerry's TC lockup values seem to have nailed the PI's personality.

The only negative I have noticed is there is almost no engine braking at cruising speed unless I have the OD off. She tends to want to keep a steady speed when lifting off the gas in OD. No big deal, I just leave the OD off unless I'm on the highway or switch it off when I notice it.

This is definately a nifty mod. Gobs of off line line torque and smooth WOT shifts that grab speed from nowhere. No kidding, for the first time I can spin the wheels enough to get the rear end going a little sideways from a dead punch, and I just got new tires last month. And I don't know if its due to the TC or the new tune, but my mpg went up a tad. Gotta love it!

- JD

[Murader03]

I just got my PI-3000 installed today .and what a big difference!!!i know im into the 12's now ,will post when i can.i used to have this neck snapping shift from 1st to 2nd even at slow speeds well its gone now ,until i get on it.i didnt know the stall speed made that much of a difference glad i had it installed :D :D . now all i got left is the water pump ,rims &tires..Thanks dennis and this site..



HEHEHEHEHEHE! I told you so! Now, "MAYBE" I wo't be able to take you from a 70-110 roll-on! :lol:

[TAF]

The only negative I have noticed is there is almost no engine braking at cruising speed unless I have the OD off. She tends to want to keep a steady speed when lifting off the gas in OD. No big deal, I just leave the OD off unless I'm on the highway or switch it off when I notice it.J.D.

I recently had what you describe above as a "negative" fixed...'cause like you, I used to drive around with OD off in the city...but I felt after spending nearly $700 on the initial Diablo Chip and having 2 "Jerry-tunes"...it was pretty ridiculous that I had to do this in the car each time...with all this "custom-tuning".

What I had Aric do is go into each parameter for the shifts and adjust them by MPH. Now...I do not hit OD until I hit 45 MPH...and I also had him adjust the 4/3 shift at 40 MPH...so you get engine braking built-in with the shifts. My car now shifts like a manual, in everyway...including some of the hardest/throw you in the backseat/neck-snapping WOT shifts you've EVER felt in a automatic tranny car. :up:

[HwyCruiser]

Todd,

Thanks for the insight on the OD issue. :beer:

I'll see if I can get this taken care of during the tuning session at Indy.

- JD

[David Morton]

...The only negative I have noticed is there is almost no engine braking at cruising speed unless I have the OD off. She tends to want to keep a steady speed when lifting off the gas in OD. No big deal, I just leave the OD off unless I'm on the highway or switch it off when I notice it.This tranny, and every other OD tranny I'm aware of will never have engine braking in OD, whether the TC is in lockup or not. That is because of the sprag-clutch that drives the OD gear assembly. A sprag is a set of oblong steel "dogs" diagonally assembled in a cage that rides between two smooth races, one inner the other outer that are the power in-and-out path for 4th gear. When power is being transmitted the dogs "bite down" between the races making a solid connection. When you let off the gas, the sprag overruns, and it's just as if there is no connection inside the tranny at all until vehicle speed is low enough that idle speed is enough to transmit power or it shifts down into third.

[HwyCruiser]

This tranny, and every other OD tranny I'm aware of will never have engine braking in OD, whether the TC is in lockup or not. That is because of the sprag-clutch that drives the OD gear assembly. A sprag is a set of oblong steel "dogs" diagonally assembled in a cage that rides between two smooth races, one inner the other outer that are the power in-and-out path for 4th gear. When power is being transmitted the dogs "bite down" between the races making a solid connection. When you let off the gas, the sprag overruns, and it's just as if there is no connection inside the tranny at all until vehicle speed is low enough that idle speed is enough to transmit power or it shifts down into third.

David,

Thanks for the explanation. I learn more about cars every day around here.

I didn't mean to infer that the OD coast was any different before or after the PI, I guess I've just tuned more into the shifting / coasting characteristics recently. It sounds like Todd's solution is the way to go for those who get irritated by it.

BTW, I'm not certain I'm getting the whole tc lock / unlock shifting sequence correct, I just know its better. Maybe someone could teach a class on torque converters... I'd sign up for that. :)

- JD

[Murader03]

J.D.

I recently had what you describe above as a "negative" fixed...'cause like you, I used to drive around with OD off in the city...but I felt after spending nearly $700 on the initial Diablo Chip and having 2 "Jerry-tunes"...it was pretty ridiculous that I had to do this in the car each time...with all this "custom-tuning".

What I had Aric do is go into each parameter for the shifts and adjust them by MPH. Now...I do not hit OD until I hit 45 MPH...and I also had him adjust the 4/3 shift at 40 MPH...so you get engine braking built-in with the shifts. My car now shifts like a manual, in everyway...including some of the hardest/throw you in the backseat/neck-snapping WOT shifts you've EVER felt in a automatic tranny car. :up:

Well, I guess if I don't get this stuff fixed at Indy next week, I guess I'm gonna have to make a trip to ATL. I'll wait till I drive Merc's set up at our next get together. At any rate, as much as I like what I have now, it's got some really rough edges that need fixed, parameter wise.

[TooManyFords]

What I had Aric do is go into each parameter for the shifts and adjust them by MPH. Now...I do not hit OD until I hit 45 MPH...and I also had him adjust the 4/3 shift at 40 MPH...so you get engine braking built-in with the shifts. My car now shifts like a manual, in everyway...including some of the hardest/throw you in the backseat/neck-snapping WOT shifts you've EVER felt in a automatic tranny car. :up:

...Note...to....self....
.....Get....Aric...to...tune.. ..tranny.....

Thanks!

john

[martyo]

...Note...to....self....
.....Get....Aric...to...tune.. ..tranny.....

Thanks!

john

John: Add to your note that he should be the only one tuning your car. The guy is truly a master!

[MYSTA KANG]

Man your ride is clean.

[TripleTransAm]

This tranny, and every other OD tranny I'm aware of will never have engine braking in OD, whether the TC is in lockup or not. That is because of the sprag-clutch that drives the OD gear assembly. A sprag is a set of oblong steel "dogs" diagonally assembled in a cage that rides between two smooth races, one inner the other outer that are the power in-and-out path for 4th gear. When power is being transmitted the dogs "bite down" between the races making a solid connection. When you let off the gas, the sprag overruns, and it's just as if there is no connection inside the tranny at all until vehicle speed is low enough that idle speed is enough to transmit power or it shifts down into third.


Have you determined whether there is a physically-locked connection between the intput and output sides of the tranny on the 4R70W, in 3rd gear? Being familiar with GM trannies, I liked the ability to have the shifter in (OD) and have the engine freewheel to idle on throttle lift-off in either 3rd or 4th gear, but have the overrun clutch kick in when (D) was selected and get full manual-style engine braking (since the TCC would only unlock with the brake pedal).

On the 4R70W w/ stock programming, if I keep the OD locked out, 3rd gear behaves the same as it would with OD enabled (provided I'm below the 4th gear upshift point, of course). Only at much higher speeds in a forced 3rd gear can I get a little engine braking, due to the reverse torque action through the torque converter, because the damned TCC unlocks the moment I lift off the throttle.

I'm still planning on getting my hands dirty with some tuning software within the next 12 months, but I'm wondering if I keep the TCC locked up on deceleration, will I still see an RPM drop the moment I lift off the gas? (I would think not, since I wouldn't have seen the slight engine braking in stock configuration with OD locked out).