There is a value called TCC Lock (and Unlock) TPS % vs Speed for both Low Gears and High Gears. What does this mean? I cant figure out if the TCC will lock/unlock if the throttle is below or above these numbers. Whats the scoop? Thanks.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
318 RWHP, 419 RWTQ
13.23 @ 107.62 MPH (2.13 60')
Southern California
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

it will unlock when the throttle passes the specified percentage.

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1984 Z51 Auto, Ported and polished intake, K&N, MSD, Ram air/Cold air intake, no cat, no AIR, no egr, no swirls plates

 

This was discussed a while back...

https://www.thirdgen.org/messgboard/...ML/001049.html

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'87 IROC 5.7l TPI - original owner!

[This message has been edited by P J Moran (edited December 10, 2001).]

 

PJ, are you still running at the .2/.1 %tps values to accomplish no lockup in 2-3? I just had my tranny built and want to address this right away. I can really tell the difference now with the 2500 stall when it locks up in 3rd. My tranny guy wanted to go back in and fix it in the tranny, but I told him I thought I could do it in the ECM. What is your low gear L/U constant settings? Doesn't really matter, right?

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'87 Formula WS6 - ZZ4 Crate TPI, Scroggin-Dickey ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel base, ported plenum, Edelbrock 58mm TB, Crane Fireball ignition, SLP cold air, SLP 1 5/8 headers, !cat, Summit exhaust cutout, Walbro 255, Koni yellows, Hotchkis panhard & LCA's, 9 bolt w/3.27's.

 

No, but it's of little consequence.

MikeT88IROC350 pointed out to me that the unlock values should probably (for the sake of consistency ) be higher than the lock values. Also, TunerCat is a little fussy sometimes, and won't take numbers outside a given range. So, I'm now running on L/U = 0.4/0.8. It works just the same, though.

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'87 IROC 5.7l TPI - original owner!

 

I checked my current bin, and I managaed to get the L/U tables all 0's for the "not in 4th" tables. Not sure how it happened, but that's where I am at. But, I am not so sure that it REALLY prevents the TCC from locking in low gears. Is there a real convincing way that you (PJ) can test for this condition? I'm not driving my car now, and I did have the tranny worked on in sept, so I haven't had much time running the car. But I could swear that I observed the tranny locking up in 3rd gear, with my latest settings.

Just thought I would pass this along.

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Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

 

Coupla ways:

1) Watch your tach as you mash the gas a bit. If the TCC's locked, the RPM's won't really budge. If not, they will immediately jump. Even if it's quickly unlocking, you will see a hesitation in the tach that isn't there if it's unlocked.

2) Your scan tool should tell you. I have an Auto Xray and it will monitor the TCC status. It even tells you if the ECM thinks you're in 4th or not. My 4th switch (in the tranny) was not always working properly, and was causing some erratic TCC behavior. It's easy to replace, if necessary.



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'87 IROC 5.7l TPI - original owner!

 

Thanks for the tips, PJ. I will have to play with it next spring when I start driving it again. But I did look at some scan recordings that I made. I do have the TCC lockup parameter, as well as 4th and 3rd gear status flags. I don't think the TCC flag is working properly. It either shows always on, or "off". And it doesn't flip like it should. The 4th gear flag seemed to work, it changed when it should have, as best as I could figure. The 3rd gear flag seemed to always be on.

I may have to contact Ease about the TCC flag not working properly.