Stop TCC unlock when coasting?

[LS1_Dragster]

4L80E, when in 4th and the converter locked if you let up on the throttle even slightly the converter unlocks then a second later it locks again when giving it some gas. Any way to stop it? What should I change to help? With my loose converter it's real annoying to have it unlock letting the RPM's jump then drop back down again.

BTW, the TCC unlock in 4th and 3rd MPH is way lower then actual MPH so I don't think it's a MPH setting...

Lee

[joecar]

Hi Lee,

4L80E segment seems to inherently do that...

4L60E segment from F/Y-car keeps it locked.


Forum member slow67 didn't like this, so he is using a 4L60E segment to drive a 4L80E transmission.

[ScarabEpic22]

Its a truck OS thing, all truck OSs regardless of 60E or 80E do this. Annoys the crap outta me on my 02 TB, I run a pretty aggressive ramp up rate to try and have it lock as fast as possible, but its still annoying.

For the SS and all T42s, you can get around it by running a car OS in the TCM. Not sure you can do it in a LS1 as the platform options might be different, but who knows. Unfortunately, there were no cars with 80Es and doing a seg swap of an 80E trans seg to a car OS will keep the truck OS issue. Boo.

[joecar]

It is possible to run the car 4L60E segment to drive a 4L80E... the TCC PWM has to be driven by the TCC Enable signal, and a relay is needed to invert one of the shift solenoid signals.

[MyM8V8]

It is possible to run the car 4L60E segment to drive a 4L80E... the TCC PWM has to be driven by the TCC Enable signal, and a relay is needed to invert one of the shift solenoid signals.


Hi Joe, I might be completely wrong here, but if he is running an after market stall with a heavy duty clutch, does he want PWM? I thought PWM had the effect of slipping stuff, and that would be the last thing you would want on such a stall?

Please correct me if I have got this all wrong. Cheers.

[LS1_Dragster]

How disappointing. I really don't want to mess with running the 4L60E code and modifying the wiring.

It seems to me that if it's computer driven then why can't EFILive or any tuner, get to the code and allow us to change it? Is it just lost in the code or something? A deep guarded, encrypted place that GM doesn't want us to know about? (Being smart ass...)

Lee

[joecar]

Hi Joe, I might be completely wrong here, but if he is running an after market stall with a heavy duty clutch, does he want PWM? I thought PWM had the effect of slipping stuff, and that would be the last thing you would want on such a stall?

Please correct me if I have got this all wrong. Cheers.He would have set the Minimum Duty Cycle table to some high value.

Note the following...

4L80E has this circuit:
- TCC PWM,
To lock TCC, the PCM drives TCC PWM to some high value.

4L60E has these circuits:
- TCC PWM,
- TCC Enable,
To lock TCC, the PCM drives TCC PWM to some high value and drives TCC Enable to ground (i.e. both required).
4L60E is further complicated by the fact that the PCM will spike TCC PWM up/down while TCC Enable is off
(the HMTG book says it parks the TCC PWM solenoid at 90%, see here (http://forum.efilive.com/showpost.php?p=39479&postcount=5)).
Edit: the TCC Enable solenoid is also just called the TCC solenoid.

:)

[joecar]

How disappointing. I really don't want to mess with running the 4L60E code and modifying the wiring.

It seems to me that if it's computer driven then why can't EFILive or any tuner, get to the code and allow us to change it? Is it just lost in the code or something? A deep guarded, encrypted place that GM doesn't want us to know about? (Being smart ass...)

LeeLee,

It seems to me that it can't be found, or deeply embedded in the algorithm, or deeply hidden...

The truck trans segments (includes algorithm) all seem to unlock on closed throttle.

The car trans segment all seem to keep locked, but the cars came with only the 4L60E.

[slow67]

Lee,

It seems to me that it can't be found, or deeply embedded in the algorithm, or deeply hidden...

The truck trans segments (includes algorithm) all seem to unlock on closed throttle.

The car trans segment all seem to keep locked, but the cars came with only the 4L60E.

I wonder how hard it would be to find? The trans segment isn't that big, and is pretty well explored. Just take 2 tunes, make them as identical as possible (1 locks up, one doesn't) and compare the binary files. This does assume that you can download the binary from the pcm, not the encrypted one used by today's modern tuning software.

Maybe even find 2 4L80E segments on the same OS where 1 locks up and one doesn't.


Another positive side effect of getting rid of the PWM, is that I bet it cuts down on the wear and tear of the PWM solenoid (common problem on higher mileage transmissions).

[ScarabEpic22]

If you can get a raw *.bin file from the PCM and then another one from a car you might have a shot. But Im willing to put money on there being a LOT more differences than just this between car and truck OSs. Yes the tables may be the same, but the background code is probably different. Very similar, but not exact.

Im not to familiar with LS1 PCMs, can you run a car OS and turn this off from within EFILive?

[slow67]

If you can get a raw *.bin file from the PCM and then another one from a car you might have a shot. But Im willing to put money on there being a LOT more differences than just this between car and truck OSs. Yes the tables may be the same, but the background code is probably different. Very similar, but not exact.

Im not to familiar with LS1 PCMs, can you run a car OS and turn this off from within EFILive?

If you have a compatible car OS, you can swap in the car trans 4L60E segment (and do the mods joe was talking about). I have an fbody PCM, so naturally, I am running a fbody OS, with a 4L60E segment on an 80E.

BTW My drive is ~25 miles, mostly highway (with little traffic) and my transmission only builds about .5* of heat per minute on the highway, when I get home its a whopping 130*F. It is about 110* when I get on the highway. It would normally be 160* when I got home with the 4L80E segment (and hover around there).

[ScarabEpic22]

If you have a compatible car OS, you can swap in the car trans 4L60E segment (and do the mods joe was talking about). I have an fbody PCM, so naturally, I am running a fbody OS, with a 4L60E segment on an 80E.

BTW My drive is ~25 miles, mostly highway (with little traffic) and my transmission only builds about .5* of heat per minute on the highway, when I get home its a whopping 130*F. It is about 110* when I get on the highway. It would normally be 160* when I got home with the 4L80E segment (and hover around there).

True, but the OP needs to run a truck OS for guages, etc with a 80E and doesnt want to rewire for a 60E. If he wanted to rewire, then do a car trans seg swap and be done, plus a few wires.

If I had a truck, Id run a car 60E seg and either a 60E or 80E depending on what I had done to it power-wise. But Ive been thinking, probably get a small car as my next car, 2 SUVs are killing my bank account for gas money. Especially since I run 91+ in both all the time (the 02's tuned for it dont worry, 08 has a LS2). Kinda want a VW GTI MkVI...:hihi: But the only tuners for them are super expensive and only canned tunes, not my cup-o-tea after having EFILive.:rockon: Or get a GMT900 Silvy, std cab short bed, drop a 427 LS2/7 (depends) and a T56. :D

[LS1_Dragster]

Actually, this 4L80E is in my 71 firebird.

I remember when I first hooked up the 0411 computer and powered on the car there was a terrible buzzing coming from the trans. It had a 4L60E program when it did this. As soon I uploaded a 4L80E tune the buzzing stopped.

By altering the wiring will it stop this buzz?

Is there detailed instructions on how to do this mod?

Lee

[ScarabEpic22]

Ah, thought it was in your Tahoe for some reason...

Good chance the buzzing was the solenoid doing something funky. If you change the wiring like Joe and slow67 said, that should go away completely (unless there's another issue, doesnt sound like it though). Its only swapping 1 wire and removing 1 I think, could try it for a weekend and if it doesnt work then go back to the 80E cal.

[LS1_Dragster]

I must be blind, I don't see where the wiring diagram is posted!

Lee