2014 Sierra BTR Stg2 L83 Trans jerking and throttle not opening

[nomsplease]

Been reading around here quite a lot and I cannot find a lot of info on why my Trans seems so affected while trying to tune this cam. I have been dialing in VVE and the virtual torque tables, and the further I go and more refined they become the trans seems to get worse. I assumed this was based on the fact that the torque model was off but changing torque tables does not seem to be making the trans act any better. I feel that I have got VVE dialed in pretty well. I havent made any changes to the MAF since im still using the stock intake and the error has not been very far off, I figured it was probably fine to leave it as is.

I have recently gotten the converter rebuilt with a billet cover and internals to prevent converter death on the 6l80. I did install a Transgo Tow and Pro kit as well, which all worked out well. I did update the shift timing tables per Transgo's instructions, and have tried with an without these changes and it did not make a different to the jerking.

The goal of this build is to tow my camper with a little less stress, I also had a DOD lifter die and why would you keep a stock cam.

Sections of concern:
47s to 1:07: The trans is jerking in every gear here, it feels like when you drive a manual and are lugging the motor. Best description I can give.
1:34 to 1:38: Throttle plate is opening more then I would think it should, maybe this is ok?
4:14 to 4:17: I tried to roll on the pedal here and the truck didnt move at all.

• Stock bottom end L83
• DOD delete with TSP valley cover
• BTR Stage 2 Truck Cam
• Springs
• 4 Degree VVT limiter
• Hooker blackheart shorty headers

Any advice would be appreciated, I am at my wits end trying to get this thing to act correctly.

[GHuggins]

Put a stock torque model from 1200 up back in it - that should help with the downshifting. Log all of the trans parameters so you can see what that "billet" converter is doing. You might need to raise your pressures and regulator settings to keep it locked. Watch silversurfer77's youtube vids for tuning the trans shift timers.

[nomsplease]

Just noting its a stock converter with a replacement billet cover and billet piston, all the rest of the converter is stock. I will check out his Videos since I have seen nothing on how to tune the 6180 at all really.
I will put the stock torque model back as well. I guess messed up somewhere if the torque model is now making the trans throw a fit.

[GHuggins]

Haven't seen too much good out of those billet upgraded converters yet. They always seem to have problems with the tcc. That's why I said you might want to log your transmission channels to see what it's doing. As for the torque model - put the stock back in from 1200 rpms up. Leave your idle like it is then smooth it back over to the original section your putting back in. It looked like you raised the map side - that controls gear hold and downshifting in the transmission. Cringer's 6 speed vids are the only ones I've seen touch on the actual shift controls for teaching. Before that we had to teach ourselves how it worked by experimenting with the tables

[nomsplease]

Ah you may be referencing when I rescaled them for a tire change. They were rescaled since I went to slightly larger tires, which I was told was important to update the tables via the tire wizard to keep the shift points correct. That?s the only thing I can see that could have changed it.

I did raise the VT table trying to get it more in line with where the cam should be, but at this point it was more stabbing in the dark trying to get anything to actually show change. Max Tq just stays under what the motor makes no matter what I change, I know this is just stabbing tables tables to try and get them do what you want though.

[Clutch]

You need to increase your "Driver Demand" tables.

When either "immediate torque" or "actual torque" exceeds "predicted torque" it's pulling a bunch of timing in order to get actual and immediate torque below predicted torque.

If you plot all three in the scanner under "chart vs. time" you'll see what I'm talking about.

[nomsplease]

Is Driver demand responsible for raising only predicted torque, or is virtual torque responsible for raising this? I have gone in and raise it a couple time now in small increments, 5% each time, to avoid any serious driving issues. I this possibly where I need to only raise the higher sections of this table to fall in line with the out of idle period of the table?

[Clutch]

Yes, Driver Demand is your way of asking for a certain amount of torque and this becomes "Predicted Torque"

You as the driver, your foot on the gas pedal, is saying (in the driver demand tables) when I press my foot this much say 50% throttle at 30 miles an hour I want the amount of torque that's in that cell on the table. Now that the car is making more torque the "actual torque" and "instant torque" start to exceed what's in the cell. So, it limits the torque to what you told it to be (what's in that cell). The more it's off (LESS than) the actual and instant torque the more the throttle will close. So, unless you want to limit torque; you always want "Predicted torque" to exceed the other two. You need to fix this first before trying to tune your virtual torque because you can't even see your peak torque at this point.

I would suggest; from looking at your scan that you go into your Driver Demand tables and from 28%-86% multiply by 1.1 to that whole part of the table. Then at 38%-86% multiply again multiply by 1.1 to that whole part of the table. So, in the end you'll have raised the 28%-38% range by 10% and the 38%-86% range by 20%. There's of course the other way to do that too. (Raise the 28%-38% range by 10% and the 38%-86% range by 20%)

Change your VT back to what it was before you messed with it.
Load the updated tune in the truck and run another scan.
Upload the updated tune and scan with the results.

[chadtunes]

I'm not really qualified to speak to this but I don't think it's the trans.. Look at the TQ management kicking in.. It's not showing detonation.. It looks like driver demand is kicking in and it's closing the throttle? then pulling timing & power?

I'm still learning but I like reading logs.

C

Screenshot 2023-05-23 164946.png

Screenshot 2023-05-23 164657.png

[nomsplease]

Thanks Clutch for explanation on that, I was confused which table was really affecting what and I always felt like the driver demand table was too low for what the truck would make with the changes. I?ll revert the VT back to stock and get ahold of the driver demand first.

Also chad finding tma that I didn?t see pulling timing there, hopefully this can get me moving in the right direction again.

Appreciate the responses all, I?ll respond back with changes and probably more questions.

[Alvin]

Been reading around here quite a lot and I cannot find a lot of info on why my Trans seems so affected while trying to tune this cam. I have been dialing in VVE and the virtual torque tables, and the further I go and more refined they become the trans seems to get worse. I assumed this was based on the fact that the torque model was off but changing torque tables does not seem to be making the trans act any better. I feel that I have got VVE dialed in pretty well. I havent made any changes to the MAF since im still using the stock intake and the error has not been very far off, I figured it was probably fine to leave it as is.

I have recently gotten the converter rebuilt with a billet cover and internals to prevent converter death on the 6l80. I did install a Transgo Tow and Pro kit as well, which all worked out well. I did update the shift timing tables per Transgo's instructions, and have tried with an without these changes and it did not make a different to the jerking.

The goal of this build is to tow my camper with a little less stress, I also had a DOD lifter die and why would you keep a stock cam.

Sections of concern:
47s to 1:07: The trans is jerking in every gear here, it feels like when you drive a manual and are lugging the motor. Best description I can give.
1:34 to 1:38: Throttle plate is opening more then I would think it should, maybe this is ok?
4:14 to 4:17: I tried to roll on the pedal here and the truck didnt move at all.

• Stock bottom end L83
• DOD delete with TSP valley cover
• BTR Stage 2 Truck Cam
• Springs
• 4 Degree VVT limiter
• Hooker blackheart shorty headers

Any advice would be appreciated, I am at my wits end trying to get this thing to act correctly.

I'm surprised no one has flagged this..

It is going into PE very early on throttle especially during your flagged area of concern.. Timing is being steady so it looks like anything your feeling might be fueling related. Its a very rich commanded PE too. something like 0.87 would be more appropriate.

This could be TCC related too.. I'd delay lock up until 5th gear, and maybe a 1300 RPM minimum. You are still locking in 3/4th and I don't see slip stuff in the log.

You have a couple codes to address
P0135 - O2 Heater Circuit (Bank 1, Sensor 1) (Current)
P0325 - Knock Sensor 1 Circuit (Bank 1) (Current)

And the VVE does not look dialed in to me. Eyeballing it.. it looks almost completely stock. I'd strongly suggest failing the MAF and tuning the VVE independently. Doing the VVE from MAF might work.. doing it in isolation definitely will work and does work wonders in clearing up odd issues like this.

[chadtunes]

Thanks Clutch for explanation on that, I was confused which table was really affecting what and I always felt like the driver demand table was too low for what the truck would make with the changes. I?ll revert the VT back to stock and get ahold of the driver demand first.

Also chad finding tma that I didn?t see pulling timing there, hopefully this can get me moving in the right direction again.

Appreciate the responses all, I?ll respond back with changes and probably more questions.

This is helping me work through this too. Can you go back to the stock file and get a good log like you posted? You changed so much it probably makes sense to go back. But this is worth a try.

I'm still learning and figuring out the VVE closed loop histogram which is ST& LTFT's + some math and it's averaged out: attached picture. Going on this information... It looks like to me that the VVE table is out of whack seeing as you're cam has less air and produces less tq at idle. The the VVE table has to much air. I'm seeing a big difference between your Mass air flow and your dynamic airflow readings. The spark timing is all over as is tq management.

I didn't want to go too big but your ass air flow and your dynamic airflow is more than 22% off. I went to the VVE table and grabbed 1000-1800 RPM and reduced by x .78 % ; smoothed the surrounding fields & calculated coefficents on both the closed and open loop tables.

So compare what I did with stock.. Or just extract those fields on VVE open and closed loop & calculate coefficients and try to get the dynamic and mass air flow #'s close.

C


Screenshot 2023-05-24 081240-VVE-STFT & math channel 7.png

[nomsplease]

The math in these tables tables are all to allow it to be tuned without needing to fail the MAF and make it possible to tune the MAF and VVE at the same time. Maybe this tune was not the one with the dialed vve tables, I had reset to stock and started again due to this trans jerking thing that kept happening. I havent had a chance to get back into the truck and try increasing the driver demand tables again. I try to get the VVE table and MAF within 5%ish, after that the LTFT and STFT should take care of the fueling from there but I always ran into the trans issue which seems to be TMA.

TMA should be all over the place from what I understand on idle, I dropped VT to 20-40 ft lbs and it always pulls timing to get down that far. Any further drops in VT did not result in any less timing being pulled so this seemed the way it was accomplishing that without going negative torque and causing even more issues. This is how I understand it anyways, if someone can prove this wrong I'm all ears.

[chadtunes]

Yea Interesting I was looking at the tune you posted.. Thats good to hear you're sorting things out.

[Clutch]

The math in these tables tables are all to allow it to be tuned without needing to fail the MAF and make it possible to tune the MAF and VVE at the same time. Maybe this tune was not the one with the dialed vve tables, I had reset to stock and started again due to this trans jerking thing that kept happening. I havent had a chance to get back into the truck and try increasing the driver demand tables again. I try to get the VVE table and MAF within 5%ish, after that the LTFT and STFT should take care of the fueling from there but I always ran into the trans issue which seems to be TMA.

TMA should be all over the place from what I understand on idle, I dropped VT to 20-40 ft lbs and it always pulls timing to get down that far. Any further drops in VT did not result in any less timing being pulled so this seemed the way it was accomplishing that without going negative torque and causing even more issues. This is how I understand it anyways, if someone can prove this wrong I'm all ears.

First, when you get to the "Driver Demand" tables, in the scanner start a new group and add Predicted, Actual and Instant torque. It will make it easier to see when predicted is exceeded by either of the other two.

Second, on idle tuning, VVE is where you should be decreasing the numbers not VT. Keep decreasing until you get the 'HIGHEST TIMING".

Let me requalify that. By first lowering VVE in the idle area; the throttle should start to close more while timing increases to maintain idle. Find the setting that gives the most advance first, then if idle is higher/lower than your idle setpoint; raise or lower VT to get it there. More timing, stronger chop and less stalling issues.