I hit a couple of weird "bugs" or issues with the transmission pressure behavior.
basically I noticed that I have lost all torque management. It used to work fine, but at some point I Must have broken it somehow.
also, sometimes EPC pressure compared to the force motor table and shift pressure table, the results make NO SENSE to me.
For example
-at 30% TPS I see it commanding an EPC of 98mV (.098 Amps or "WOT" pressure) occasionally
-at 100% I have a full 90PSI Of shift pressure commanded in the tune but it drops to 70% or 80% Commanded pressure for some reason anyways.
Found out:
The torque (and shift pressure) was dropping on shifts due to the torque management being implemented.
Whether or not timing was actually pulled I am still unsure, but the computer definitely thinks it IS working, and torque is being "removed" by the computer which afflicts the transmission pressure.
so for now, to keep the transmission from slipping, I added torque signal to the regions of force motor current where the torque management tends to pull the shift from, roughly 74-78% region. In the future I will hope to adjust the torque vs timing table so that will be much less reported drop in torque on a shift.
As to the torque management, please read the next post #2.
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The rest of this here (#1) is just me discussing with myself to remind my future self of what have been happening...
After reviewing the logs carefully it looks like the Computer is 'predicting torque' which is why the torque signal sometimes rises quickly at low TPS% positions. For example at 30% TPS I've had the torque signal jump near max pressure, then fall back down when the tps stayed still for a moment.
This is a good thing, I guess. It means you can't "surprise" the computer with a sudden throttle input and slip the transmission, in theory.
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Next I noticed that the "enable max line pressure for failed MAF DTC" selections (there are 3 of them) do something very strange when turned to "yes". They don't do max line pressure but they DO raise it some, I was seeing about 10-20% more pressure everywhere with them turned on to "yes".
Weird, but useless, I turned them all back off of course. I only turned them on because in my old files, with the old version of HPtuners, those selection boxes did not exist yet, and so they were all set to "yes" by default in the original file. So I wondered if that was turning on or off the torque management since it works in the old file with them set to "yes". But apparently all it did was bump the torque signal pressure.
.. I'm going to upload an old file and gradually bring in all my changes and see if I can figure out what killed all the torque management.
For some reason I feel like this issue is a bug or hidden table or selection I can't see. I notice that my options changed when they updated the software and some features like closed loop randomly started working out of no where until I changed some new tables that suddenly appeared. I think a table "suddenly appeared" that disabled torque management and I can't see it.
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update: 2-21-21
To try and fix this issue I've:
1. replaced Crank position sensor
2. crank position re-learn (several times)
3. Used beta version of HPtuners to detect any hidden settings
4. Tried various combinations of DTC Involving the MAF, "no error reported" etc... to see if one setting would work
5. Also tried various combinations of setting in the tune file:
A. shift time (tried 0.00 and 1.25 and everything in between)
B. torque removed vs timing and commanded vs torque removed (those inverse tables)
C. DTC max enable line pressure for maf fail *ON* and *OFF*
D. other stuff I forget
6. disabled the PRNDL and tried "P & N only"
7. Loaded old tune files where torque management used to work and working backwards tried to see why it stops...
Tentative Conclusion:
Oh you are going to love this. So after all of that and perhaps 10 hours of fussing with tune, scanner, data logs, hours of review and consideration....
It looks like torque management IS working, I am not sure whether something I did "fixed it" or whether its been "working" the entire time and I've just not been able to catch it on the timing logs because I was logging too many other things at once....
which begs the question: IF it IS working then why are my 1-2 shifts so violent and wheel spinny?
I believe the answer is simply that the 4l80e is such a heavy powerful transmission that even with the engine "shut off" during a shift, there is still so much energy in the rotating mass and with those brand new 1-2 intermediate clutches in the transmission plus that .098A of transmission torque signal pressure applied, it just obliterates the tires and bring back in the power to keep em spinning. It also doesn't help that when torque management pulls timing to negative advance while the shift loads the engine that basically spools the turbo even harder, boost jumps up 2-3 more psi during a shift because of that, so there is even more power once the timing comes back in. Yesterday I nailed it at 10mph and it downshifted to 1st and started spinning at 3pi of boost, then it hit 2nd and the tires REALLY started going, smoking them down the street probably 50 feet till I let off around 40mph probably. Its pretty crazy how fast and smooth the 4l80e can shift.
I still need to verify that this is all true. I will update once I get a definitive log of this situation. And then I will attempt to lengthen or increase the torque management of the 1-2 shift without pulling out too much transmission pressure to give it a snappy yet hopefully more sane 1-2 shift.
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