[GraniteBlue05]

It kept bumping the line pressure up, honestly rather slowly, until finally that tcc slip started getting back in line. I think there's just a limit to its learning range and once the fluid degrades beyond a certain point, it wont 'learn' to hold pressure beyond some specific upper bound for a given quantity of torque, it's all very crazy how it's related.

Quite a bit of it isn't visible to us in HPT, we don't actually know how the algorithm relating to TCC pressure works. 20 years ago we would have a GM engineer on the forum who would happily tell us, but those days are gone in favor of endless non-disclosure agreements.

Also the HPT forums kinda suck, nobody shares info any more, it's all a giant crap shoot. Still at least they simply don't make content as opposed to 20 new 'what lift should I get on my commuter truck' or 'what useless tough looking metal crap should I bolt on to my commuter truck' or 'O how cool I can pay 45k over 84 months and finance all that metal crap on an oem truck' threads a day ;-)

When did I become a bitter old man.

Careful . . . someone might use the "cranky old man" label. :wink2:
Thanks for taking the time to show the factual operation of these events.

What you said early about the TCC *not* being simply on/off or engaged or in slip mode coincides with some commentary I read on another forum. I was aware that the TCC is not like the earlier "lock up" torque converters from 25 or 30 years ago or so since I worked in the automotive ECM/PCM industry.
But as to the exact particulars. . well your parameter lists show exactly what is happening and allowed. The thing that remains curious to me is the latest *moisture" related cause GM is saying causes the shudder. It still sounds like a design issue of some sort especially since the 10 speed does not seem to suffer this or at least not as much. Maybe it uses a different TCC design or programming for slip?
All this wizardry is getting a bit much when it is put out in the market and yet does not seem ready for Prime Time . . . ::chevy::


Here is a cut and past from another forum . . note the reference to the *variable* solenoid operation.

" - The GM 8L45 Hydramatic Transmission is part of the powertrain in the Cadillac CT6, CTS, ATS, Chevrolet Camaro and perhaps more vehicles under a different name. This questionable feat of backwards design and engineering was accomplished with variable force solenoid technology, speed sensors and a processor executing hundreds of calculations and commands every 6.25 milliseconds. Clearly, this is not often enough, as evidenced by the ride experience inflicted on the driver and passengers when the thing desperately hunts for the proper gear and any gear will do … to lurch forward. With all that technology it performs far worse than the bands and torque converters of that our grandparents enjoyed in the 1960’s and later. In 2016, General Motors was simply not ready to evolve past the 6 speed transmission but that didn’t stop it from going ahead and cursing entire fleets of its new vehicles with the crudest powertrain component in its history. - "

 

[GraniteBlue05]

- - - at the same time it sure doesn't hurt to have certs, it better than nothing.

But does that cert have "Retsyn" ? :grin2:
Sorry . .. I couldn't resist. A short "fresh" break in this dialog.