I seem to be experiencing tcc slip that is causing RPMs to surge up and down. Happens in second gear. Doesn't seem to happen in other gears.
Truck was tuned at a shop and they said it's all good... it obviously feels wrong when you feel the RPMs surge, the truck almost bucks in the middle of a pull.
Logs attached. I also contacted Circle D for advice.
You have TCC disabled in all but 4-5-6. So not sure how you are getting tcc slip in 2nd gear when it is programmed not to apply.
right - especially at WOT it shouldn't be locking ever. 4-5-6 should only lock at part throttle.Originally Posted by TheMechanic
OK so if it is locking up in 2nd gear you need to use the scanner and see if the TCM is commanding TCC apply. If it isn't you have a mechanical issue and it's time for a trans tech for a mechanical diagnosis. Maybe a failing TC
I don?t know that it?s locking, it?s just showing slip momentarily. I?m honestly not sure what that means though.
Without you specifically stating you have two potential slip data. TCC and (undefined ratio) gear slipping "clutches".
You may want to check all of your trans codes and re enable them to see if the TCM recognizes a slipping component or it's just a normal condition.
Last edited by TheMechanic; 06-08-2023 at 07:19 PM.
TCC Slip - see attachment. You have slip at the bottom, many peaks. And the peaks reflect in the graph at the top where Red is RPM. You can see how the car would physically react to that slippage. It's not a smooth RPM curve.
Annotation 2023-06-08 204351.png
Get into 4th gear and command TCC on and if slip is zero
Will do that - new to the software so I need to figure that out but I will do it over the weekend.
I was able to go back out yesterday for an additional log and found that in 3rd gear it's really smooth with no peaks, and smooth pull. So it seems to be only in second gear it acts up.
I will say that maybe it's worse going up a hill (anecdotal, probably need to "prove" that). I was almost wondering if it I should "overfill" it as others have suggested and see if that helps. It looks to me like I do lose one or two psi of line pressure when the slip occurs. Maybe slamming my foot on the pedal and sloshing of fluid is causing my fluid pump to not pickup fluid well enough?
Last edited by maniactom; 06-09-2023 at 09:39 AM.
You have DoD enabled and the DoD TCC tables are not zero'd out. Zero them out.
Additionally, your trans tcc hot table is locking the TCC at 20 mph in second gear. Probably want to max this table out (or make it match the normal tables). Check tables [TCM] 15242 & [TCM] 15243 & [TCM] 15249. There may be a few others, so check them all.
A standard approach will give you standard results.
My Tuning Software:
VVE Assistant [update for v1.5]
MAF Assistant
EOIT Assistant
Embarrassing. Thought I looked pretty thoroughly. Obviously I didn't. Good catch. Guess that's why it is so important to copy and paste into each and every pattern.
Thank you!
DoD is mechanically deleted from my vehicle. Should I just disable this? Will I ever get into this table if it's deleted and disabled on the engine tune?
My assumption is that the ECM can still command DoD to be on if it is enabled in the tune. It doesn't have knowledge that it was mechanically deleted. And if it is commanded then it will allow slip.
A standard approach will give you standard results.
My Tuning Software:
VVE Assistant [update for v1.5]
MAF Assistant
EOIT Assistant
It's disabled in the tune under Engine -> Fuel -> Lean/Fuel Saving. So it should never go into DoD.
Hmm what the heck. Sorry about that! You are right. I would still disable [TCM] 402 though for consistency.
A standard approach will give you standard results.
My Tuning Software:
VVE Assistant [update for v1.5]
MAF Assistant
EOIT Assistant
Thanks I'm going to do that!
btw - I've been watching your 6l80e videos on YouTube. Very informative!
Do you (or does anyone?) know what constitutes Hot Trans? When does it use that table?
This I do not know and I have always wondered myself. I have a few theories:
1) The most likely case, is that HPT does not expose this setting for us to see or use.
2) A long shot might be it piggy backs off the TCC adapt max temp ([TCM] 5651 - TCC Adapt Trans Temp Max). This should be easy to test...set it to a temp that the transmission will exceed in normal driving and change the hot shift tables to see if the behavior changes.
3) Another long shot might be just like #2, except that it uses [ECM] 4160 - Oil Temperature High (in Engine Diag > General)
A standard approach will give you standard results.
My Tuning Software:
VVE Assistant [update for v1.5]
MAF Assistant
EOIT Assistant
That all makes sense to me - I was thinking it would be based off the Transmission Oil Temps.
According to my logs I'm not shifting in that table, but obviously it's better to adjust those tables and match them just in case.
while i dont have a solution for you. i can tell you that the whole tcc not locking up completely is something in the tune that can be turned on/off. However I still believe it's something that has not been exposed in neither HPT or Efilive.
I recently had a car in for tuning that only had a 2500rpm stall. The convertor was constantly showing up to 50rpm of slip at light load. So i compared it to a tune i had done before that i knew had no issues with lock up (same os, but different factory transmission calibrations). So i used the other file as the baseline then copied all the exposed parameters from the original tune, then flashed.
Instantly stayed locked & showing negative rpm slip.
Same pressure, offsets, speeds.
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