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I'm having issues understanding WOT TCC lockup in 8L90 cars. Seems as we add more power they tend to slip more under load in higher gears. But what baffles me is that we can make two pulls 15 seconds apart. In one pull, there might be 11% slip. In the very next pull 15 seconds later there is none.
Here are two screen shots taken 15 second apart. Same car. Same converter. Same tune. Same minute even.
Attachment 99916
Attachment 99917
Am I overlooking something basic?
Let me guess circle D converter?
It's aftermarket, but not a Circle D. I have tried increasing TCC Pressure Apply Ramp and TCC Max Pressure tables, but neither seems to make any difference at all.Quote:
Originally Posted by Ben Charles
Is that a known issue with circle d? I have a c7 with one and i cant get it to lock for shit.Quote:
Originally Posted by Ben Charles
I’ll tell ya right now they don’t have their 8l90e converter figured out
^this
Had mine in for about 10k miles and never got to use higher gears due to slipping while commanding 0. Ben saw this first hand and I'm now going back to a stock converter.
YANK converter?
It's aftermarket, but not a Yank. I have tried increasing TCC Pressure Apply Ramp and TCC Max Pressure tables, but neither seems to make any difference at all.Quote:
Originally Posted by tunerpro
Here's the most baffling part. We can do three pulls on the same tune, in the same scan. Two might slip like crazy, and the third shows no slip at all. Here are screen shots from the three pulls (all at 85 mph) we made in the same scan with the current tune.
Attachment 100469
Your first post, I thought it might be software - maybe that's part of it, but your second post looks more like the TCC clutch is failing to hold power consistently.
I wonder what the TCC manufacturer thinks about it. A lot of those companies recommend you either run it unlocked, or locked and NOT slip the TCC clutch at ALL. Of course, the OE software tries to make it a smoother experience for the driver and decides, seemingly randomly to allow some amount of slip while it's locked. So the first thing that needs to be done here, is the TCM needs to stop deciding it wants ANY amount of slip. Desired slip should only ever be zero when the converter is locked.
The second thing is whether there's enough apply pressure to the TCC clutch. I didn't see that data posted here, but it sounds like you've made some calibration changes to affect apply pressure.
If neither of those things help, then I'm thinking you're overpowering the TCC clutch (or it's failing for some reason). If you are running a vehicle where you can calibrate the power output level reliably from the ECM (like a turbo car), then I would see if engine power reduction causes the issue to go away. Also, I'd check whether it happens in lower gears. This might help determine if the issue is mechanical in nature.
Mine did it the same on 7psi as it did 13psi. Circle D pro billet triple disc
Were you able to find a resolution?Quote:
Originally Posted by DENALI62
Thanks for the good suggestion. We will give this a try!Quote:
Originally Posted by tunerpro
Not exactly. I am currently replacing my trans and will be going back to the stock converter.
Tapout Tuning, do you have a tune file you can post and the scan? Have you adjusted the Trans> torque management> Torque reduction to Disable all but default, CT and Garage. Speed CTRL Terminate = speed ramp. Limit TqMGT > for upshift and downshift to None. Did you disable the TCS?
Make sure you have the PCS1 CMD pressure, PCS 2, PCS 3, PCS 4, and PCS 5 CMD pressure, fill Pressure CMD, Time of latest 1-2 shift, Time of Latest 2-3, 3-4, 4-5 Shift,
Trans shift mode, oncoming Clutch, TCC Line pressure, trans engine torque, trans slip RPM, TCC slip, TCC desired slip, Trans input shaft rpm, Trans output shaft and in trans misc. add the trans turbine rpm PIDS.
Clear your charts and put those into groups [Latest shifts group], [C1-5 PCS group], [TCC Line pressure, CL Fill pressure, trans input and output group], [RPM speed latest shift cur gear group] make one for [TCC slip,TCC desired slip, trans turbine rpm, tcc line pressure, trnas current gear] too.
The Pressure control solenoids or PCS is what makes the shift happen. One is oncoming the other is off-going others are steady. What did you change for the Shift pressure>Base shift pressures TCC On tables and TCC Off? You do not want to update the whole table here add only up to 4thgear. Add 30 psi to the LAST 4 columns, @ all rpm range and in each 1-4th gear TCC on and the OFF tables if you haven't.
Have you updated the General shift> Shift Inertia for the single gear changes ...no skip shifting adjustments but add 2 to whole single gear tables. This is a bit subjective and firmness is personal, but it may help with the slip. Did you 0 out the TCC desired slip AC off 1-5th? You also may have the shift times tooo fast for your hardware. Has the tranny been rebuilt for the desired shift timing? There are mechanical limits and if the tune is faster than the physical mods/stock parts it will be unpredictable. Really watch the PCS data in scanner when it slips.
Have fun.
This is excellent input and I really appreciate it! I will try all the above recommendations and get a new scan for you. Do you have an email address I could send it to?Quote:
Originally Posted by Hondaeater
I'm really curious to see how this ends. Is there a way you can upload the log/tune so I can look at it? (I don't know very much at all, but I would like to learn). Or email me?
I have a c6 but I'm looking at doing some funny stuff.
If the converter was failing to hold the power, wouldn't you see trans fluid temps higher on the slipped pulls vs the non slipped pull? EDIT: Locked pull will obviously have different temps than non locked.
Would the converter be hotter than regular slipping if it was failing???
Me too. I went ahead and kept my circle d triple disc in. I'm not worried about wot, my issue is with higher gear cruising. I get slip at the slightest tip in while commanding none in 7th and 8th gear.
That seems odd, I don't recall ever seeing anyone have this issue with c6's??? Then again, I never really looked through the vette forums too closely. 6l80e and 8l90e converters are the same diameter, right? I assume similar size... Circle D has a pretty good reputation...
Have you asked Circle D about it?
They told me to send it in for inspection but I haven't had the opportunity to. I really think I'm not getting the pressure to the tcc that I'm commanding at least at light load. Anyone with any experience with this if you could point me I would be so appreciative!