Ive been playing with the TCM tunes over the pas couple days and im almost 100 precent satisfied with it... except for one thing.

The Torque converter will not stay engaged at 0 TPS... it doesnt matter what I change or do to the tune it will not stay engaged... For example I can be doing 70 mph down the highway and if i let my foot off the gas the TC will unlock and the truck will coast down the road... However even if i keep my foot about 5-10 TP the TC will stay engaged and I can feel it slow the truck.

I have went through every single table looking for what is causing this, but after about a hour I gave up. Has anyone had experiance with this?


If/when I get this tune done im going to throw it up in the library... Its so much faster in the city due to the TCC staying engaged (you dont get that lag untill it had time to lock)... which means no delay.

I tuned it in such a way that anything over half throttle will give you the Tow haul shift points (with a exception to 5th gear, I went and increased the speed needed to shift into it). At first I tried to copy all the tow haul tables over to the normal maps but it would not shift worth crap in the city... and I found myself having to play with the throttle to get it to happen... But now Its awesome.. Get the responsiveness of the Locked TCC but yet have the shift points in such a way that if your foot isnt into it it seems stock.

But if anyone knows what I have to change to keep the TCC locked at any TP range it would be appreciated....

Im loving this EFI Live thing :)

I'm not sure why one would want to have the t/c locked all the time unless in tow haul mode, for instance when you drive a manual trans truck and let off the throttle decelleration starts immediately and at varying degrees dependant on engine rpm. which kinda eliminates the coasting concept. When going down slight grades I don't want to have to keep spending fuel to maintain speed. If you want to race around all the time I guess that is fine for you, but I set my trans tuning up to allow 2 selectible options if you will, with the use of tow/haul button like it is from the factory. Yes the tuning has to be altered for increased performance but I don't want hard full throttle type shifts all of the time. Just my $.02

Now if we could just get this selectible tuning for the lbz module life would be great.

To answer the question to keep the t/c locked just push the button on the gear selector and it will keep it locked from second gr. up.

I am going to guess your transmission is still stock Mitco? I noticed night and day difference in TC feel when I got an aftermarket one.

I haven't altered my trans tuen at all and I think it is great. Maybe I've never seen what a good trans tune can do, but I have zero problems with the way mine operates... except for my half throttle shifts, but thats my crappy TLIQ table in the ECM tune thats causing that. it needs fine tuning.

yes its stock... and thats why I am doing this...

If your driving around the city and you want to punch it you gotta wait for the TC to lock up... and while its doing so the truck has next to no acceleration... which is what im working on.

Im trying to get the best of both worlds... the tow/haul mode and just the regular mode... im also getting the transmission to say outta 5th a little longer so when I get on it I dont have to worry about it shifting to 5th so soon (unless I let off the throttle below 50 Precent... then it will act normal and complete the shift... So far its working very nicely and i wanna get some feedback on it when im done)


RoadKill... I can see what you mean, but if i can get it to stay locked then I can change the unlock speeds to eliminate the engine breaking effect under certian speeds. For instance Im not going to have the TC stay locked in 5th because like you said when your on the highway you want to be able to coast.

But in all the other gears driving around the city, how often do you coast? I personally like the positive feel of a locked TC when comming upto a set of lights... it creates less wear on the braking system and on hot days would help cool a hot engine. I would set the unlock speeds so they would not interfere with the idleing or shifting, so that it would stay on for some time before unlocking. Not instantly like it does right now.


FMOS I wanna just go for a ride in a built tranny...lol, Come this summer when i get outta university and start working hopefully ill be able to afford one... I know I need one...or will need one in a bit... But for now im trying to make this one work for me...

Well, if your back in wandering river or mcmurray or anywhere between edmonton and here we could arrange a ride in a truck with a built tranny. Nothing special though, it has my home brew tuning in it that I think is the cat's ass but is probably just shiat.

Not to sound like an idiot, but what about just driving in tow/haul? That does almost exactly what your talking about, it even keeps the TCC locked at 0 TPS until it gets below a certain speed/rpm. I think its around 1400-1500.

The only thing I would be interested in doing is modifying the 5th gear shifting parameters so that it waits a bit longer like you mentioned... with 35" tires it often shifts a bit too early and then resorts to lugging and making smoke before it picks up speed haha.

FMOS... Initially the reason I did this is because My tow haul switch went for a crap... so then i set out to copy all the tow haul tables over to the regular tables... but didnt like the way it handled. (I should have mentioned this earlier... but when i did that the TC did stay locked)... But when I wasnt on the throttle in the city the shifts were way to high and I had to play with the throttle for every shift...

So I set out to make it so that with anything over 50 percent TP I get full functionality of the tow/haul, and anything below I still get the shift points raised a tad... but not so much that you have to work with it to get it to go in the gear you want.



What I suggest you do FMOS is even when your not in tow haul get the converter to lock anywhere between 32-40 KM/h... This change alone has made my second gear so much more responsive (unless your in towhaul the TC will not lock in 2nd)...

I got to open up the truck today on the highway... and changing that 5th shift point made a world of difference... I can actually get on it without having to worry about the 4-5 shift unless i get over about 120km/h... or I let the TP drop below 50... I may even go and raise the 4-5 shift point a little more... because the engine is still making alot of TQ in the upper rpm range...


If you would Like Send me your stock TCM tune file for your truck and Ill change it to what I have mine set at... I would love to hear some feedback on it. I never changed shift times outside of GM specs so no need to worry about damaging anything... I strictly stayed to Tow Haul Shift specs (did not drop it any more than that)... and Modified all the shift points (both WOT and otherwise)... and of course the TC lockup.

Do a search in the electronics section, The TC switch issue is common and can easily be fixed. My "little orange wire" rubbed through under the little plastic column clip, and I had to do a little splicing myself. ;)

I to have been playing with the trans tune. In normal mode i have the TC to lock up at 22mph in every gear and unlock at 18mph. I have also droped the shift points from 0-75% TPS so the truck shifts below 1500rpm. With a slight heavy foot.

You will have a slight increase in EGT's but no more than 100 or so. I have had a few people drive the truck not knowing i changed anything. They will come back saying they love the way it drives. I have noticed a few times the rpm is not where you need it so i do have some more work to do.

Yea I know what you mean jstrese... I to got some work to do... but would love to figure out how to keep the TC locked reguardless of the TP and only have it rely on the TC lock/unlock maps that are present in the Tune... but for some reason as soon as the TP goes to 0 the TC will unlock (which is ok for 5th gear... but i want it to stay on for all the other gears)....

If im driving through the city and I let off for a second... Then I want to get back on it quickly It irratates me to have to wait for the TC to lock... I want it to get up and go...


Just changing the shift points and TC lockup the truck seems so much faster and it seems to shift and respond so much better. If you figure out how to keep the TC locked let me know... Ive looked through every table and searched tons of forums... all without luck.

I messed with this a little but to me it just causes problems. Like locking the TC then unlocking it then shifting then locking again.

I started thinking if it was more efficient to lock the tcc in lower gears driving normal then GM would have made it that way.

But even with the stock shift points at WOT. It seems like the trans wastes a lot of time between downshifting and not locking the TC.

I think the reason Gm didnt lock the TC in the lower gears was to make it more smooth... when the TC is locked in the lower gears it takes very little throttle to slap your head back against the seat... whereas if its unlocked its way smoother. It would not be more effiecent to keep it unlocked... As a unlocked TC creates alot of heat (another reason why it doesnt lock untill the fluid temp is 35 degrees... if it stayed locked the tranny would not heat up (as fast anyways)...


Like I said if i keep even 5% Tp on it while accelerating my TC stays locked all the way through...

Could it be D5057 (minimum RPM) that is causing it to unlock. I think mine stock is set to 1300 so if when you let off the throttle and it drops below that it would unlock.

It could but usually When I first let off the RPM's are above that... for instance crusing around in 4th the rpms are about o I dunno lets say 2K... but once I let off if the TC would stay locked the RPMs would slowly drop... but the unlocking TC lets the rpm drop down to idle...

Thought about that already... but thanks for the idea..

Not much help here but i've attempted to do the same thing with the same results.

After looking around a bit it seems that the issue is EFI Live has not tapped into all the parameters that are found in the TCM... So there is something over-riding all the maps that we can edit...