Large Throttle Blip When Engine Torque Source Switches From Idle To Axle

[L83Crazy]

Started off with the provided Whipple tune. Worked great with minor adjustments for months. Swapped to larger throttle body and intake. Dialed VVE good, made large airmass adjustments to help with idle timing and have made some small adjustments to virtual torque. Still learning and understanding the torque and airmass stuff. MAF has not been calibrated yet and still running speed density. I believe the MAF is my last step once I go back to closed loop.

Anyway, I am getting a large jump in axle torque when leaving from a stop. I seem to get this once I try to dial my Virtual Torque table in at idle to match the predicted ENG TQ command of 6. The closer I get to my idle timing around 10-15 and my engine torque to line up, I get this large TQ request leaving a stop and idle surge in park. I am clearly missing something here.

Other than this the truck has made amazing improvement and driveability is great. Cant seem to wrap my head around this one.

IDLE TO DRIVER.hpl
TRYING TO DIAL IN THE TORQUE AND IDLE 4.hpt

[GHuggins]

I've got 2 right now doing this myself. Not exactly like yours, but nevertheless. I've dialed the torque models in and even gone as far as shifting things extreme one way to the other. Mine will do it sitting still in gear randomly or just when put into gear. I've dialed in idle air, adaptives, you name it. I still haven't gotten it sorted. I know it's in the torque model and most likely the map side, but I've shifted and even gone as far as balancing the models as perfectly as I can. I haven't gotten it yet. Funny enough I've had this problem in the past. usually you can work the map side of the model and fix it and for me it's always one single cam that causes it. The btr 2. Then like I said I can usually get it sorted on the odd OS's that it does it on, but these two are kicking my arse...

So for what it's worth you can usually dial in all of the above mentioned and settle it out. I'm going to try something different on one of the one's I've got causing problems, but most likely it won't work if everything so far is an example...

[L83Crazy]

Well dang, the guy who helped me get to where I am is stumped. lol I also tried going to extremes of all different variations with torque model and virtual torque. Also some bigger VVE adjustments and other things. I had a hunch its something on the MAP side or maybe driver demand. Mine is consistent with switching from idle to axle tq leaving a stop. Axle torque shoots up from 100-200 to 1300ftlbs, timing goes to high 20's and my throttle opens abruptly to achieve this request all before I even hit 700rpms. I am unable to find a good description of operation on how axle torque works or how to manage it.

Funny thing is, if I leave my adjustments where I have 0-2deg timing at idle and -13 engine tq, it will idle and leave a stop great. I may accept the idle here and call it if its too much of a hassle.

[GHuggins]

The problem is on a DI motor or any fuel burning engine as far as that goes in order to increase torque it will pull timing - this is actually how the adaptives work for rpm and idle control, so if timing is already low then torque is technically high and this is why it won't pull with the timing operating at a lower setting. The two I'm dealing with now are the same way. If I have idle timing at 5 or less the problem doesn't exist. I don't like idle timing that low, but I've gone as far as having idle timing in the 30's with really detuned adaptives and it will still yank every bit of that out to pull timing to 0 for whatever it's doing. I've requested some research into axle torque request be done by Will if Will would even be able to find anything on it or related to it as nothing is really labeled in the coding. I've also tried shifting DD idle values, but nothing I've found will work around this short of setting idle timing low at least on these two. Again, it's only one specific cam that causes this for me so I don't know if there's a specific correlation there or not.

[GHuggins]

OK, I may be speaking too early on this, but I may have gotten this figured out. I knew the issue was airflow related, so the first thing I went after since nothing immediately tune related was working - and this was what I was wanting to test out in my previous statement was throttle area and not the one visible to public, but the one in the background. I basically lowered it for the idle region about 15%. This took care of about 30 % of the issue on it's own, so I figured I was on the right path. However any further adjustments made no difference and the in gear issue may have been worse. I then started watching and going through some OE logs I had from tuning OE setups. Something in particular stood out to me. Min airflow in the cals was about 2 to 3 g/s over actual and a stock tb will idle anywhere from 11ish % to 20ish % open whereas with a cam or AM TB they idle less than 5% in some instances which was the whole reasoning for going after the throttle area in the first place. I have always been setting the min airflow table up near actual airflow so this time I set it 2 to 3 over actual and ALL of the blips in gear while at idle were gone and most of the blip pulling into gear was gone. AGAIN I've only had this issue with this one cam and on 3 different engines now.... One of which I was actually able to fix reasonably easier. I then went after the torque model and completely counter shifted it positive in the idle area. The end result so far - slightly positive torque at 0 pedal with double digits on requested and only a slight timing dip when pulled into gear on top of a 13ish to 19ish degrees of timing at idle with the 13ish being what it now dips to when put into gear.

I still have to redial in the density table and off idle torque model on top of the DD and what not tables that correspond, but overall pretty happy to finally know something on it. Then of course I also adjusted the adapts and min timing tables slightly for their best operations at the moment.

Anyway - FWIW

[L83Crazy]

Thank you for the update! I rarely get time to mess with my tune so its hard for me to get on here and report back. I'm going to digest more of what you said and see what I can figure out, thank you for the great info. After a bunch of trial and error, so far what has worked for me is to lower my torque reserve table by 10%. It seems to be very sensitive. At first the idle would dip and it did not like it. However I noticed I was no longer requesting an insane amount of axle torque off the line. After a good long drive it settled and was stable. (I'm sure I could reset my throttle air comp to help as well.) I also took a little out of the DD table at 0-8 APP and MPH. Probly not necessary but also seemed to tame it off the line. During all this I was messing with my virtual torque, VVE and also my torque model. Different variations of this yielded no change to correct the issue but was needed to get things happy again. My idle has never been better. I'm going to continue to drop the reserve til I go to far then dial back. Then incorporate other small adjustments along with the info you provided.

[GHuggins]

What I posted above worked on the one truck, but the second with the bigger TB is being a touch more of a fine stepping pain. Same changes affected it, just not to the degree that the first truck saw. I've almost got it under control too after spending a month of one or two revisions a day trying different shifts of tables. Don't necessarily like how I had to do it, but it's working. For it, the biggest plus was to lower the throttle rate/area table 3% for the tps idle areas (yeah didn't like more or less - wound up with something close to a LT1 after comparing them) then I actually lowered the DD idle cell down to something again like a LT1 uses and adjusted the VE overly rich by 10% to help hold the throttle open only for the idle rpms up to 1000. I also adjusted the TM until idle torque and timing were desired (timing's in the low teens and torque is up to 35Nm's) and then I slowly increased the map side high load until almost all of the timing dipping and rpm issues were gone. Now I'm fine tuning torque and fueling via the density table. Seems to have it working right at the moment. His bigger ported TB has been a real pain to get right on this setup since with it just barely twitching seems to make the idle logic throw fits in this controller with it's truck background corrections. I tried messing with the reserve like you did but it didn't seem to help. I may try re lowering it and seeing how it does now that I have everything else really close.

When they're driven like that and smooth out it's usually because the torque models shift toward one another. You might be able to log delivered torque and see which way the models shifted then reload the tune and see where they were originally and make corrections accordingly... I know this one's been a pain, may even be running the same tb as yours.