The way the stock AUJP cal works, the TCC is unlocked (allowing the motor to return to idle) at ~ 0% TPS. I've already disabled the TCC unlock in DFCO, but my TCC still unlocks when i take my foot off the gas. I'd much rather it stay locked.
Anyone got any pointers? Is this a simple switch I'm missing, or do I need to go modify the source?

 

There are also parameters for unlocking the TCC at certain speeds, and also in low/4th gears. I believe the stock values for my AUJP were 34 unlock and 37 lock or something around there. I increased them both by 4 MPH in order to keep my TCC from locking too soon, which lugs the engine.

 

Do you like tranny overhauls?.
The stock TCC material is slightly more robust then sawdust.

It's a very soft material to shop TCC shake. It also shreds off with any real abuse, and those lil fibers just plug up various orfices so the tranny fries.

The only way I got a 700R4 to last with spirited driving was by going to a non lockup. Nowadays you can get a kevlar'd multi disc converter to take the abuse, but figure on $800 for a decent one.
200R4s different all together.
If you want to get things right to do the TCC properly try writting to Bruce Toelle out in Ca..

I'd suggest not getting too creative with the TCC stuff. While you might tune it a little different from stock keep their strategies.

There is alot to be improved upon in the stock code, but you have to have the right parts to start with.

 

thanks for everyone's responses. hopefully this will clear things up a little.

I already have a pro-built 700r4 with all the transgo stuff and a 9.5" converter. It's NOT a multi-disc converter.

problem 1 with stock calibration:
TCC is forced locked at 75mph even at WOT.
solution:
raise TCC forced lock threshold to 255mph
why:
I don't want the converter destroying itself trying to lock at WOT at 75mph. In fact I don't EVER want the converter to lock at WOT.

problem 2 with stock calibration:
at any speeds below 75mph, the TCC unlocks during decel and relocks when i lightly get back in the gas
solution:
???
why:
it's annoying as heck and causes repeated unlock/lock cycles when in the 40-75mph range. Now I could raise the TCC lockup MPH points (and have tried it), but I don't want to drive around all of the time with the converter slipping and making a bunch of heat. I use the 40-75mph range extensively (in-city driving AND highway driving in moderate traffic).

problem 2 is my biggest concern. the constant locking and unlocking can't be good for it. I just want it to stay locked during 0% TPS. that would solve my problem. I know the TCC clutch can handle it, because it handles it great when i'm above the 75mph "forced lock" threshold...it will compression break from 90mph to 75mph great!

Basically, the stock logic is fine for me with the above two exceptions. Problem 1 I can fix easy, problem 2..still working on it.

I know this is all a bit controversial. I guess I am going with a "modified" grumpy motto: give the transmission (and TCC) what it wants. In my case, driving the car, I know the TCC needs to stay locked during light throttle cruise conditions, and because light throttle in my case covers a range of 0%-20% TPS, this includes staying locked during decel.

I'll let everyone know the code change I make (if any) to achieve this.

thanks

 

A single disc 9.5?
Please reconsider, what I've written.

Keeping the TCC locked is going to put alot more load thru it, and with that limited amount of area, only makes the situation worse.

When you crack out of the gas, there is a Sudden snap reversing the loadings thru the drivetrain. releasing the TCC allows them to disapate. Keeping it locked shocks the TCC.

I went thru 4 trannies over what turned out to be TCC issues.

 

grumpy,
what's your thoughts on GM's policy of forcing the TCC always locked above 75mph? I frequently and often use compression breaking above this speed, so in effect, i am already doing this, just only at high speeds. Is there maybe some difference that makes it OK at high speed, but not ok in the 40-50mph range?

Part of the reason it bothers me is because i have a slightly loose converter. (2400 stall). here's a typical scenario:

cruising along at 50mph, in OD, TCC locked, maybe 1600rpm. I let off the gas. The TCC unlocks, RPM goes straight to near idle. Then, I get back in the gas, and because the TCC is unlocked, the RPMS quickly jump up to near stall (2400), then the TCC engages and pulls the motor back down to 1600 (maybe a bit less if MPH has bled off). As you can imagine, this can be quite a driveline jolt, the TCC clutches are matching up an 800+rpm difference! Do you think the jolt/abuse from this is not as bad as(and thus prefferable to) keeping the TCC locked through the on-off-on throttle transition?

My line of thought is that the TCC clutches can absorb a bit of a "bump" of driveline lash when the converter is already locked up, but that the constant and repeated 800rpm engagement would eventually wear out the clutches.

thanks for your input!

 

Check the parameters at $8315 through $8318. This is from
the ANHT hac, should be the same or close to AUJP.

The params at $813A and $813B may also be of use in this
instance.

RBob.

 

That's to keep it from overheating, with the stock hydralic circuit there is no tranny cooler without the TCC being applied.
With a small revision to the circuits, a non lock up TCC also can give a full time tranny cooler feature.

For any really serious automatic work, the 200R4 is the answer, unless you want the weight of the 4L8E which just leaves everything else in the dust. The 4L8E just gives the right gearing, and is PCM programable. A 9.5 multi disc'd 4L8E is the best you can do with a 4 Spd Auto. Now if you want a 5 Spd then we get to the Allison 1000 series.........

 

You might look at the code.
In the GN code, there is a TCC retard that retards the timing when the TCC first applies, and then it decays out.

The TCC is used to get the crivetrain to 1:1 to min the Torque converter slippage, ie it's solely a MPG deal.

As small as your's is it will probably always be noticeable, and they had to keep it's action quick so there is no slippage, because it is so frail. What kills an auto tranny is slippage, and the heat caused by said slippage.

Sorry to get so far off list.

 

IMHO - I think the best solution for a street/race car is actually the TH400 with a gear vendor's overdrive. This unit is very very stout. Plus, you never have to worry about converter lockup (just use a big tranny cooler!!) and a TH400 is easy to rebuild for almost any local shop. The 4L80's are expensive to rebuild and its difficult to find someone who can rebuilt one correctly. I will definitely be going this route. The only problem is money. The GVOD unit alone is over 2K

Tim

 

That 2K takes care of the E Overhaul.

You just got to use a Flash type PCM, and play with a E series tranny, you'll never go back to the old stuff again.

Shift feel, individual gear shift points. Stuff you can only day dream about with a 400 is executable in a 8E.

Th400 with any stall, isn't to great on the street, they just have too much slippage, IMO. While the 400 and 8E share the same HP loses, at least the 8E doesn't generate as much heat once the converter locks. Remember heat detracts from pushing the car down the road, You want to make heat in the engine, but o where else. 8E tranny, and 12 bolt rear end......

 

The 4L80 isthe way to go, imo.I'd like to adjust shift firmness through the pcm.Light years ahead of the th400 or 700R4.I wish there was a low buck pcm kit.The gear vendor stuff is cool though.

 

yikes, and here I thought making the ECM work with a t56 swapped in would be difficult. Now it sounds like the t56 would have been the easiest best way to go....

sorry to get so far off topic everyone...