If i want my convertor to lock up only in 4th gear, do i set my other parameters to 255 (or something similar )? Heres what i have on those:
tcc lock low gears= 38
tcc lock hi gears= 32
tcc unlock low gears=36
tcc unlock hi gears= 30
tcc mandatory lockup=80

Would i change the mandatory to 55 or so, and put the others at 255 (or out of range) so it wont lock?

 

I really wouldn't eliminate the lockup, just delay it. What do you have for gears? What do you have for a stall speed on your convertor? Why do you want to eliminate the lockup????? Also, what computer/bin file do you have????

 

I dont want to eliminate it completely, i just want it to lock in 4th gear only. I know there is a way you can do it mechanically inside the trans, but i thought you could do it through the computer as well. Im trying to keep it from cycling in and out so much.
My convertor is stock (89 rs) and im using the ANLU bin right now until i can get some datalogging done. 8746 ecm, tbi.

 

As you surmised I would change the low gear allowed to lock MPH's to 255. Could also change the low gear TPS% to unlock/lock to 0. The mandatory MPH lock I wouldn't change.

Can also change the hi-gear MPH and TPS% for better TCC action. Lo-gear defines 2 & 3, hi-gear defines 4th, or overdrive.

Great paper over on diy-efi concerning TCC control. Aimed right at the '8746 ECM.

RBob.

 

Wouldnt happen to have a link to that, would you? I cant make heads or tails of the archives.........

 

Try this:

http://www.diy-efi.org/gmecm/papers/

 

What RBob said but if you've got a strong engine and rear gears with the tcc-kickdown "mod" you might move the manditory lockup speed up to 65. Also, if you drag race the manditory lockup will lock the tcc even when you're WOT. This can be death to a tcc. I've got my manditory lockup at 110mph and it's always locking up when I cruise. I then used the tcc lock/unlock tps tables to keep it from unlocking when I squize into "passing the slow truck going up a hill" mode. From that I modified the tcc unlock parameters so it doesn't unlock when I lift or hit dfco. That was really annoying with the loose tcc and slow highway cruising. Lift and it would unlock, rev to 2800rpm, couple seconds later latch and pull the engine down to 2400rpm EVERY time I lifted on the highway. It was abusive to say the least. With a stock tight tc it might not have been as noticable.

 

Well, my 350 is a stock reman unit, and im running the stock convertor. It just seems like its always locking and unlocking when it shouldnt. I havent yet begun to mess with the tables (just burned my first chip yesterday). It just seems like the only time i would want it locked is on the highway (50+ mph) and unlocked if i were to step on the gas or brake. If only it were that easy, i guess.

 

If you've got 3.23's or lower (numerically) gears in the rear then I would do what you want to do... lock only in 4th. Do exactly what RBob suggested by moving the lockup/unlock speeds in low gears to 255.
Then, if you're using the ANLU bin I'd look at importing the ANTT or some automatic f-body bin's tcc tps lock/unlock tables. I had to do that because the ANLU was doing all sorts of weird things, and that was with the stock tc and 3.08 rear gears.
Import the tables from AXKT, those feel really good.

 

JPrevost, i have a stock converter & i find the unlocking at the slightest lift of the petal very annoying, then touch the gas & it locks back up, also very irritating. with my rear gearing in overdrive i only spin 1550 rpm in lockup at 70 mph, even my cruise would unlock the TCC on flat level ground. its so much better being able to lift off the gas & having it stay locked up till i get down to under 50 mph. i have you & RBob to thank for that

i can imagine what its like with a stall, i probably would have put a toggle switch on it in the first week.
im still working on getting it to unlock how i want when i get on the gas to pass. a stock motor kind of struggles at such low rpm.

 

OK,
On the way home this morning i noticed exactly what you guys are talking about, and i need to know what you did to make it stop! I lift my foot off of the gas at around 50-60 mph and it unlocks the convertor, then i ease back on it and it revs for approx. 2 or 3 seconds and locks back up. AAARGH! Is there some way to keep it locked until i press, say, 5/8 to 3/4 down on the pedal? I have to mess with the tps stuff, dont i?

 

That is the decel unlock TPS% threshold and relock delay. Should all be in that paper.

RBob.

 

Does this 8746 ecm also have the "stay locked in DFCO" flag function like in the $8D ?
That would keep it locked while coasting and also can increase milage. Then the unlock is TPS commanded only.
I like how it works that way on mine.
Just wondering.

 

Yes, mine says "DFCO TCC unlock?" and i have my flag as "set"......does it need to be "not set" and then adjust my tables like rbob was saying?

 

Yes, un check, un set, however you want to word it

Then, look for;
TCC - Coasting hi TPS threshold
TCC - Coasting TPS threshold
set these both to 0.

 

Burned a new chip and tested it on the way to work. Awesome!! It works just like i want it to. It didnt unlock a single time when i didnt want it to, and drives kind of like a 5 speed.

 

Reading this post got me motivated to try to figure out once and for all how the TCC works. Read the Robert Rausher article and started looking at how my tables and constants are set for 165/6E/ARAP/TPRT. The article is very good and I followed along and understood everything until I compared the article information concerning low and high gear tables to what was in the ARAP tables for low and high gear. Rausher says,
"An example would be: with the TCC locked and the vehicle road speed at 40 MPH, the TPS% needs to exceed 28% (72 * .39) before the TCC will unlock. Once unlocked the TPS% needs to fall below 14% (37 * .39) for the TCC to relock."
So, I look at the ARAP bin and the "TCC Lock Speed vs. %TPS" table entries are higher than the "TCC Unlock Speed vs. %TPS" entries. I would expect this to be the other way around based on Rausher's example. To try to be a bit more clear on this, ARAP has:
TCC Unlock Speed vs. %TPS TCC Lock Speed vs. %TPS
MPH %TPS MPH %TPS
... ....... ... ........
60 60.94 60 92.19
52 45.7 52 85.16
44 32.81 44 64.84
... ........ ... .......
etc.
I cannot understand how this should work. If we look at 60 MPH, what it's telling me is that the TCC will unlock (if it is currently locked) at 60.95%TPS (this part makes sense). But if I reduce the %TPS at this point, there is nothing telling the TCC to lock back up. It's telling me that I must increase %TPS TO 92.19 to get the TCC to lock back up. It would make more sense if the TCC would unlock at the 92.19 %TPS (although I would probably set this lower for my application) and stay unlocked until the %TPS was reduced to 60.94 where it would lock back up.
Can someone please help me understand what I'm missing?

 

CriSSes, most likely the tables in the hac are labeled backwards (or look to be backwards). This is a common problem. The table with the higher values will be the TPS% to unlock (if locked). Then the table with the lower values will be the TPS% to re-lock (if unlocked).

HTH's,

RBob.

 

Darn, and I thought I had one on the General! lol!
Thanks RBob
Mangus, could this be a TPRT issue?

 

I'm new to tuning and still trying to figure this out...
I have 3.70 gears w/ 2800 Vigilante stall causing a constant lock/unlock during light cruise, very annoying.

I've lowered the " TCC Unlock % TPS Vs. Speed" (cut in half and then raised to approx 2% above the lock settings) but havent tested yet, will do tomorrow.

I do not have the "DFCO TCC unlock" flag as described above with $8D. I'm using S_AUJP.V2/8dm2 and TPRT. The only flag I see close is labeled "Switch 18 (VSS M/AT U-TCC I-MAT VSS CCPE) BIT 3 - UTCC". Can someone point me in the right direction so I can minimize the unlock/lock I see at light cruise (<8%TPS). Thanks

 

"Also note that the GM
700R4 (4L60) transmission does not route fluid to the cooler unless the TCC is locked."

Is this true?
I don't think it is.

 

Only partial fliuid flow occurs to the converter when not locked.

Full fluid flow occurs when locked, if your trans has been built competently, it should have full flow all the time.

so yes runnign a converter unlocked that is stock will cause a lot higher operating tempature than locked.

later
Jeremy

 

Fluid is always flowing to the converter and the cooler. Isn't the majority of the heat generated from the converter caused by the slipping? The fluid is redirected to apply the tcc. I don't see how you can only get partial fluid flow?
How would you modify it to obtain full fluid flow?
I am not trying to say your wrong but I am confused it just doesn't seem to make too much sense.

 

LOL

I understand what u r saying.

Has to do with the actual fluid flow inside the transmission.

I'll trace the fluid flow in my ATSG manual and see if I can explain it better.

And yes the majority of heat does come from the converter slippage when not locked up, especially at speed.

later
Jeremy

 

Dumb question time;

I know what a torque converter is but what exactly is the tcc and what exactly is the point of locking it up?

 

TCC = Torque Converter Clutch
Locks the converter to the crank basically so there is no slippage.
Makes the car feel like a stick sometimes when decellerating and keeping it locked also gives better milage.

There was a post about a year ago that we went through all that cooling stuff if more fluid passed when engaged or not.
I had posted a picture of the flowpaths and everything was cleared up.
I don't remember all the details and searched like crazy this morning but couldn't find it. I'll keep looking.

 

The 305 caprice AXKT does feel really good on the TCC. I am using those in the G20 with 3.08 gears. It keeps the TCC locked in 4th up some good hills and eliminates the annoying cycling in 3rd that the ASWD 350 calibration had. My cruise RPM is only at 1,700 @ 70 with a 5,000 lbs truck and the aero of a brick. TCC was overly active until I switched to the AXKT ECM. My converter is a 2,000 rpm stall and it used to hunt between 2,200 and 1,700 rpm at cruise as the TCC cycled. I am sure that was abusive as well.