2012 CTS-V 6l90 TCC pressure dump after apply?

WTF is going on here ? I've noticed this while using TUTD and manually locking 3rd for a pull as well as 5th lock and 6th lockup at times. seems randomish.... i recently refreshed the trans in this car (Circle D Stage 4) and converter and while logging its will go through the shifts hit 5th and apply the TCC to around 80 ish psi ( been playing with that ) and then you will see it dump to 17 psi , the slip will rise to 6-700 and then the TCC pressure will ramp back up to 80? I haven't tried turning off adapts yet but that might be my next step .... an thoughts ? is this like a checking strategy ? feels terrible.

Keep raising up the first desired pressure column till you're happy with the initial bite of the converter. Then max out your 300 column and smooth down from there.

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Originally Posted by hjtrbo

Keep raising up the first desired pressure column till you're happy with the initial bite of the converter. Then max out your 300 column and smooth down from there.

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Did you look at the logs? . It?s happening at steady state

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Originally Posted by noobers8

WTF is going on here ? I've noticed this while using TUTD and manually locking 3rd for a pull as well as 5th lock and 6th lockup at times. seems randomish.... i recently refreshed the trans in this car (Circle D Stage 4) and converter and while logging its will go through the shifts hit 5th and apply the TCC to around 80 ish psi ( been playing with that ) and then you will see it dump to 17 psi , the slip will rise to 6-700 and then the TCC pressure will ramp back up to 80? I haven't tried turning off adapts yet but that might be my next step .... an thoughts ? is this like a checking strategy ? feels terrible.

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I think you might have a problem's with your MAF signals. It seems erratic and when the computer decides to drop the TCC pressure to get some slip the short term fuel trims on both banks go up to 15-17 positives.

As-designed by GM. See my comment in this post about tcc regulator gain.

https://forum.hptuners.com/showthrea...0e-in-a-patrol

Didnt look at your log, so Roberts suggestions should be considered as well.


Edited to add, I cannot stress enough my level of distaste for this strategy. Ok now, off my soap box.

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Originally Posted by NotSure

As-designed by GM. See my comment in this post about tcc regulator gain.

https://forum.hptuners.com/showthrea...0e-in-a-patrol

Didnt look at your log, so Roberts suggestions should be considered as well.


Edited to add, I cannot stress enough my level of distaste for this strategy. Ok now, off my soap box.

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This OS doesn't use those 2 scalars by default.

Version 4.12+ will show it.

https://i.imgur.com/nO5XAFH.png

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Originally Posted by TransGo Robert

I think you might have a problem's with your MAF signals. It seems erratic and when the computer decides to drop the TCC pressure to get some slip the short term fuel trims on both banks go up to 15-17 positives.

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Its hitting the VE table and transient fuel.

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Originally Posted by noobers8

Did you look at the logs? . It?s happening at steady state

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https://i.imgur.com/MnQufix.png

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Originally Posted by hjtrbo

This OS doesn't use those 2 scalars by default.

Version 4.12+ will show it.

https://i.imgur.com/nO5XAFH.png

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I?m not sure even if I turn it on if it will even work ?.

You leave it off and use the desired pressure table

Much worse using this method

Ok.

After much testing, I decided to try the offset/gain function @ 1.5/80psi and it is a little rough on apply but the drop out is no longer there. I?m not sure what?s going on while using the desired and apply ramp
Table but I?ve tried going from close to stock all the way to very elevated pressures with no fix for the drop out ?. Looks like I?ll be using the offset/gain function going forward .

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Originally Posted by noobers8

I decided to try the offset/gain function @ 1.5/80psi and it is a little rough on apply

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That's what sux using those scalars.

I'm looking into why the desired pressure varies in the code, I still have a way to go. However, the reg gain / offset is simple and commands as advertised.
Desired Pressure PCS Command
https://i.imgur.com/L8HdvHs.jpg

Reg gain / offset PCS Command
https://i.imgur.com/rs6QLpU.jpg

Yeah ?. But at this point it?s the lesser of two evils I feel. I did use the adapt min/max to knock down cruising lockup pressure with success so far! I set a -32 min and am running around 50 psi on 6th lock up at 70 mph with a quick rise to 110 under any acceleration? I?ll take it for now I guess.

Consider disabling adapts (all fields) and give the desired pressure table another go if you haven't tried that combo already.

I had tried that as well , it seemed to work if i recall but with elevated pressures at all times ... might be worth revisiting and trying to lower back down the desired table. its to bad we can get a decent pid to monitor where at on the desired tcc pressure table we are at ?

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Originally Posted by noobers8

I had tried that as well , it seemed to work if i recall but with elevated pressures at all times

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Don't fret about the elevated pressure. It's just a number. The TCC apply circuit is feed from the line pressure solenoid so you're not always putting high pressure on the converter. All it's doing is holding the TCC PCS wide open

That table does make sense. Even though we can't measure; TCC pressure is a function of PCS1(Line) and PCSA(TCC) command pressures.

You can also increase the low line pressure region for increased TCC clamping as well. That table is well worth your time persisting with (adapts off). It is possible to tame the initial bite, then ramp up the pressure for good clamping force. Depending on converter frictions work also needs doing in the apply speed tables; some converters bite too hard no matter the pressure, therefore the enabling apply speed is only allowed at light throttle positions.
https://i.imgur.com/12ZJfGJ.jpg

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Originally Posted by hjtrbo

Don't fret about the elevated pressure. It's just a number. The TCC apply circuit is feed from the line pressure solenoid so you're not always putting high pressure on the converter. All it's doing is holding the TCC PCS wide open

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Just to be clear, the lock-up solenoid is not fed line pressure, it is fed AFL which limits the pressure feeding all the solenoids to 110 psi. For anyone wanting to know what the actual pressure is to the clutch, as long as everything in the transmission is factory, the solenoid output pressure times 1.363636 minus 26.5 equals the real apply pressure on the lock-up clutch.

Hey Rob,

Just with respect to the TCC circuit I've always thought it was:

pump => line_pressure => line_pressure_reg_valve_PCS1 => converter_feed => converter_reg_valve_PCS_TCC => converter.

Can you please let me know where I'm going wrong?


https://i.imgur.com/zsQDjVM.png