CI GS

What have those of you with larger stalls done with the TCC lockup? I'm in the process of dialing in my tune now with a FTI 3600, and have gone from one extreme to the other with that.
Firstly, on my original tune, the TCC lockup seems to have been pretty much stock, i.e. TCC locked at low throttle input in 2nd through 6th gear. The only downside to this was that the car would tend to "lug" a bit at slower speeds, like a manual trans car will at slow speeds in too high a gear. My thinking on a fix for this would be to adjust the shift points slightly so that the car doesn't stay in 6th (or 5th) at too low an RPM. What I like about this tune though, is that with the TCC locked at slow cruise, it's impossible to detect that the car has a high stall converter and so mileage and TFTs were generally unaffected under normal driving conditions. So, my TFTs were staying at around 175-185 degrees max, even with some aggressive driving and start and stop driving mixed in.
The new tune that we're working on has the TCC unlocked in every gear at low throttle/slow speeds. I think it is programmed to lock the TCC at higher speeds in 4th at WOT, but otherwise it's unlocked. However, the car now feels like one of my old carbureted cars with a B&M Super Holeshot 3500 - it flashes easily even when accelerating gently up from a stop to say 40 MPH and when I'm cruising at anything between 25MPH and 40MPH (which we do a lot of down here) the converter is constantly slipping. Consequently, the mileage has taken a huge hit and the TFTs are now averaging over 190 and I saw 215 degrees or so yesterday. I don't know much, but I know that high temperature is the number one killer of auto transmissions. I can only imagine that doubly applies to the 6L80, which has its TCM housed internally (computers like high temperatures even less).
I know that a lot of folks believe in not locking the TCC with a bigger stall, presumably because it will fry the clutch (been there, done that with a single disc Yank) but I don't think that it makes any sense with the multi disc clutch converters, as I thought that was the purpose of their multi-disc design?
I'm not looking to start any controversy, but would be interested in any discussion by folks in the know who have high stall converters with the A6 and have tuned specifically for the higher stall.

realcanuk

I think it is a matter of preference. I have mine locking only in 5th and 6th, just because that's what feels best driving it. With my 3.42 gears, it just locks and unlocks too much in the lower gears.
I do have it lock in 4th only when I use the paddles, because sometimes on an open winding road I will just keep it in 4th for a while.

CI GS

Thanks for your reply, realcanuk. I think you're right that it's a matter of preference, but preference is probably dependent on (or at least influenced by) each of our driving conditions as well.
I have 3.42s now as well, BTW.
Most of the roads down here have a 25, 30 or 40 MPH posted limit and we have more registered vehicles than residents so we do have a lot of traffic to deal with. We have decent roads but with lots of roundabouts (our government loves to run us around in circles, apparently) so a typical drive out from where I live involves quite a bit of slow and stop and go driving and so a lot of time is spent in 2nd, 3rd and 4th at slow speeds and low throttle.
So, I would like to lock the converter up at low throttle input in every gear (except 1st) for the reasons already stated, so that when I'm just gently moving off or cruising around, the motor doesn't have to flash/rev constantly to get or keep the car moving. I realise that part of the problem is that I have a 3600, as opposed to a 2800-3000 stall, which would probably make this a non-issue for me.
I understand what you are saying though, about the 3.42s making this difficult because the shorter gears require more shifting up and down at slower speeds than a taller final drive ratio.
I am therefore wondering whether the TCC can be programmed to only very briefly unlock to allow the upshift or downshift through the lower gears, at low throttle input? I will see what my tuner says about that.
My only worry with this would be if this could somehow damage the clutch, but with a triple disc and the softer engagement of the ECCC in the 6L80s, I can't see this being a problem, especially if it's confined to low throttle input. It would also be beneficial to mileage and transmission fluid temps as well. If the TCC were programmed to disengage at anything above, say, 25% throttle position, I think this would be what I'm looking for. I would be very grateful to hear from others as well on what they've done with the TCC in their tunes.
Thanks again for your input.

realcanuk

I only have a 2800 stall so like you said the issue is much less for me.
The lockup is speed based, not throttle position. It does unlock for shifts, unless you program it not to, which isn't suggested. I tune mine myself so I do have some knowledge of what is involved, although I don't do it for a living, and am no expert.
Where I live there are a lot of small streets, speed bumps, and stop signs. When in the area I usually just use the paddles and leave it mostly in second.
Maybe you could try having it lock in 2 , 3,and 4 when using the paddles, and use them when in those congested areas. When in paddle mode I have it set that it doesn't shift to 1st unless I come to a dead stop, so even at most stop signs it just remains in second as long as I am rolling even a little. 1st is basically useless as far as I am concerned.
Good luck and let us know what you figure out.

CI GS

Thanks man. I had forgotten that the TCC lockup is speed-based (read that somewhere on these forums before) so I guess that puts my idea to bed, then!
But, if throttle position doesn't come into play, then I can't figure out how my old tune was working the way it was, because it locked the converter at slow speeds, but once I got on the throttle hard or went WOT, the converter would flash as if the TCC had unlocked?? I hope it wasn't slipping the clutch like that?!
I'll take up your suggestion about programming the paddle shift mode that way with my tuner. I hope I can find a solution to this or I may have to change the converter. I bet that's what he's going to suggest...

tblu92

All shift points and ALL TCC lock-ups and unlocks are commanded by 2 things in the tune
1. Throttle Position
2. MPH
You can't have it both ways -Awesome 3600 stall acceleration and awesome MPG
I understand that you want it to seem un stalled and have low trans temps and better mileage---
GM locks the converter from 3rd gear on up (normal driving throttle)
3rd gear at 32 MPH
4th gear at 32MPH
5th gear at 38 MPH
6th gear at 44 MPH
Basically it depends on your car's use---Most common tuning wants the TCC to only lock up once you are on the freeway so at speeds at above 55 MPH
A performance tune would normally be to DELETE all lockups except 5th and 6th gear and to raise both those to ( min throttle position ) to be 48 in 5th gear and 58 in 6th
So the converter would be locked at any speeds over 48 MPH only
Locking the converter earlier and in lower gears makes the engine lug around town---It may raise the trans temps a little--but lugging your engine is far worse on your car as a whole--
The low gear shifts happen so quickly anyway that the converter is not slipping for very long anyway----
My experience has been as I said to unlock it thru 4th gear and set the 5th gear to 48
and 6th gear to 58---
To me this is the best all round setting---still gives you the acceleration of your stall in the lower gears but above 48 MPH the converter locks and the temps cool off and the MPG goes up---I have owned many C5's C6's and now a C7--and have set them all similarly
All were stalled from 3000 to 3600 ( except for my C7) left stock stalled
ALSO at WOT the stock tune locks up at 66 in 5th and at 84 in 6th
AND UNLOCKS during all shifts anyway !!

CI GS

I pulled this picture of a page from the factory service manual off another thread on this topic that I found on these forums. It describes how the ECCC works and GMs logic for slipping the clutch slightly to ensure smooth engagement of the clutch. As I understand it, the multi-disc clutch in my FTI converter was developed specifically to deal with the way the ECCC in the 6L80 works.
I've also read that GM programs the converter clutch to lock up earlier than actual stall speed of the stock converter, in order to improve mileage. After all, if the clutch only locks up above stall speed when the converter is "locked" already, doesn't that make the TCC redundant?
I have personally observed how this works with my previous tune with the new converter and I liked the way it worked and I especially liked that at slow speeds and low part throttle, you couldn't tell it had a high stall converter. It sort of matches the NPP exhaust: mild at idle and ferocious at WOT.
Like I said earlier, the only thing that was a bit annoying about that tune was that it would lug in the OD gears, simply because, IMV, the trans was staying in those gears rather than downshifting into a lower gear. Surely that can be addressed by the tune.
BTW: I noticed this "lugging" with the stock converter as well. I also know that this is partly caused by me cutting the radiator shroud to get fresh air to the Halltech "CAI".
I don't understand why I can't have the TCC locked at lower speeds and low throttle position - perhaps not as low as stock, but at least lock it in 3 and 4 at low throttle and program it to unlock at higher (say, >25%) throttle input and WOT? How does that hurt the trans? Again, the old tune (which my current tuner said was close to stock) locks the TCC at low throttle and in those gears (just like the stock tune) and the car drives better, had much better mileage and transmission temps. And the TCC still unlocks and the converter flashes and the car launches the same as with the new tune once I step on it or go WOT.
To me, that's the best of both worlds, and maybe I do want to have it my way, but, after all, that's why I paid for a custom tune.
Please note that we don't have freeways down here, so locking it at 49 + mph is of little use to me most of the time. As I said before, I spend a lot of time at low throttle input and in the lower gears, and I don't want to drive something in traffic that sounds like a manual car with a slipping clutch.
As the tune is now, it's miserable to drive (unless I'm at WOT) and it's starting to sound like I shouldn't have wasted the money and time to change the converter.

CI GS

I have a correction to make. I took a look at my old tune and it looks like the TCC isn't programmed to lock up in 2nd at all, whilst in 3rd it will lock up at 31.8MPH at anything below 25% throttle position.
I can't view the new tune so I have no idea what's done to that, but I can tell that there is no lockup in any gear at slow speeds/low throttle.