VTT tune theory, can tuning experts confirm this?

[GHuggins]

I’m not using anything already in the scanner, either, as it isn’t explicitly useful.

Isn't that the truth

Let me know how everything turns out. I personally keep getting hung up on the math due to what can be logged vs what you need to know to even considering getting something close. I've looked into and looked into ways to calculate torque based off of engine displacement, fuel consumption, timing, air consumption, exhaust flow, compression and so on and so on. Keeps coming back to needing a dyno and even then being able to lug it in idle, which if you have an auto in these newer ones is virtually impossible as I haven't found a way to lock the tcc below a certain speed. It always kicks it out. Probably another background table.

[TriPinTaZ]

I've gone round and round with all of this stuff for years and to this day. I still find that my own intuition and simply following the torque PID's vs Desired Torque PID's and keeping a cushion on both adding and removing torque, make the ECU happy. Automatic Transmission cars are much more sensitive to the torque model. Airmass and VVE directly affect their respective Virtual Torque Models. I personally find it easier to leave the MAP Virtual Torque model unchanged or at least mildly changed for specific reasons and using the VVE table instead to affect that side of the torque model. The reason behind that logic is that typically the idle MAP changes with a cam but a lot of things under load still make a pretty accurate base torque model and there is a lot more granularity in the VVE table. The Airmass Virtual Torque side needs a lot more attention, especially if your touching the MAF curve....which is always touched. You always want Zero Pedal Torque around ~0 so that it has room to add/remove torque for the A/C, alternator load, power steering pump(in some cases) or when you put it in gear for Automatic Transmission cars.

Building custom tables and maths are also very helpful in dialing things in. Dynamic Airflow is important to pay attention to even if you have to set the dynamic airflow value to very low RPM's so that the ECU favors the MAF at all RPMs. VVE is still referenced in this case. Just when I think I have it figured out, I run into a car with a cam I haven't seen before and all of my methods only partially work and I have to make other changes for the cam to play nice. Sometimes the client wants some crazy chop added to a baby cam because its "cool". That throws everything we know about idle tuning right out of the window.

When it comes to Driver Demand, Gregs tool is very interesting. I think it is a quick way to get you a pretty good base DD table. I seem to have the best success when I keep it simple. I log torque PID's and measure them against Driver Pedal Torque and try to keep things in a certain "cushion" so that the pedal feels good to the driver. I don't like tunes where the tuner solves the issue by making 50% driver pedal equal 100% Throttle Position. It makes for a poor driving experience in my opinion.


I suppose TLDR; I still do it the old fashioned way. Custom graphs and intuition. I started tuning 20+ years ago and I still learn new things often. I only wish that HPTuners made a better effort to define more things in the Gen V platform instead of relying on paying users who then need specialized staff or help to locate User Defined Parameters. Then the ones that want to share the info with HPTuners might actually get a table added to the Beta. Unless you're a big name tuner that sends a TON of money towards HPTuners direction, they don't really care. I suppose there isn't anything in it for a For Profit business. And if you're wondering who gets the attention, its the very small group of shops that got Global B access.....as if the rest of us aren't intelligent enough to use it and open comprehendible tickets for bugs and issues. It's slightly offensive. But its not like any of us are going to go running to EFI Live. HP Tuners has no down side. ok ok offtopic. I'll get down off my horse.

[DSteck]

You still need a known somewhere; that's what a dyno output (whether engine or chassis) is for. Otherwise, it's all guessing and hoping the final effect is good enough. When it's truly right, everything will fall into place.

I'm one of the people who isn't likely to share, but I do speak up in topics like this sometimes to remind people to never think that what they're doing based off a hunch is truly right and accurate. That isn't meant to come off rude but rather just a reality check to keep trying and don't be complacent. Skewing PE was the accepted method way back when because it got a desired effect, but we can all agree it was not right. The reality is that doing it right is getting exponentially harder as ECMs become more and more complex. The tools needed to do it right don't exist to the aftermarket unless somebody goes out of their way to make it. Anybody tuning a car these days should know how to do surface regression as that's exactly what virtual torque and virtual VE are. I won't even go down the rabbit hole of neural networks because those are black magic and lies, and anybody qualified to make a PROPER trainer is already employed by somebody likely working on weapons. Lol.

They define what they can, but face it; they don't know what they don't know. Neither do end users. The guys with the know-how to reverse engineer the system aren't out there tuning cars, so they don't recognize what problems come up or limitations everyone hits. When a tuner runs into that wall, they don't have resources to fix it themselves so they shoot in a support ticket. The problem, again, is people don't know what they don't know... and it's not a quick "oh here's the limiting factor" ordeal. It can take hours and hours to find what's holding things back. User Defined Parameters relies on having an A2L unless you can decompile a BIN file and roll through the code yourself, but even then, you won't have annotations for what routines and cal values do. I get stuff added pretty readily because I can tell them what the table is, what the axis labels are (whether linked or fixed), what the scaling is, what the units are, etc. Their job becomes really simple at that point. It's just business and how it goes. I get requests constantly from people wanting things defined, and they don't even know what they want defined; they just have a hunch or assumption of what might exist, and usually it doesn't actually exist but is rather buried behind a number of related tables that don't function at all how they think. It's not about how much money anyone spends but rather how much information you can provide to begin with. There's a marked difference between "Hey, I want a table that does this" versus "Hey, here's this table that I know exists, here's how it is formatted" when getting things added.

TLDR; it isn't that black and white.

Global B... I'll give a little sympathy as I raised an eyebrow at some of the people included. I don't sell very much hardware and don't purchase a ton of credits because I do not publicly do cal work anymore, but I was included. There were a number of places included just because they bought in. Dumb, but ultimately they can do whatever they want.

[smokeshow]

OR could you or Jake better explain what the different torque readouts are that the scanner is showing such as 0 pedal, predicted, axle and so on and maybe perhaps what might directly control these?

In case it has gone unnoticed, I don't get on and explain things much anymore. Once upon a time I'd enjoy teaching...but the overwhelming hubris from those with youtube channels making money on the views trying to argue with singular anecdotal success stories using their 'custom' methods have taken the enjoyment out of it. Debate simply has no place in science. Dave and I swap info and work together on projects...but that's because he is one of the few that respects the science and engineering behind the scenes.

[Cringer]

In case it has gone unnoticed, I don't get on and explain things much anymore. Once upon a time I'd enjoy teaching...but the overwhelming hubris from those with youtube channels making money on the views trying to argue with singular anecdotal success stories using their 'custom' methods have taken the enjoyment out of it. Debate simply has no place in science. Dave and I swap info and work together on projects...but that's because he is one of the few that respects the science and engineering behind the scenes.

Debate, as in questioning everything, creating a theory, and testing that theory and using empirical evidence has everything to do with science. The problem is that people get suck in the mindset of "we have always done it this way, so it must be right" or "this is the accepted way and no debate is allowed" is where problems come from. Back in the day doctors didn't wash their hands before surgery and the first person that said there are things called "germs" was labeled as crazy. Or in the not too distant past when everyone said smoking tobacco was healthy for your lungs. Debate is healthy and necessary.

Now if you'll excuse me, I need to turn on the scupper on the SS uTube.

[smokeshow]

You confuse debate and peer review... They are not the same.

[DSteck]

Debate, as in questioning everything, creating a theory, and testing that theory and using empirical evidence has everything to do with science. The problem is that people get suck in the mindset of "we have always done it this way, so it must be right" or "this is the accepted way and no debate is allowed" is where problems come from. Back in the day doctors didn't wash their hands before surgery and the first person that said there are things called "germs" was labeled as crazy. Or in the not too distant past when everyone said smoking tobacco was healthy for your lungs. Debate is healthy and necessary.

Now if you'll excuse me, I need to turn on the scupper on the SS uTube.

When it comes to factory ECUs, there’s the fact of how they’re coded along with the physics of engine control, and then there’s guesses. I spent years guessing until I got to look behind the curtain. Now, all I can do is shake my head at what’s being shared out there.

[Cringer]

You confuse debate and peer review... They are not the same.

I think publicly sharing on Youtube, Facebook, and this forum theory, formulas, etc to reproduce results constitutes peer review. The results from the peers across the world are overwhelming that it works. I have had no one say it failed them. If there is a governing body over "how to toon" I would gladly submit it there for review, but that doesn't exist.

[Cringer]

When it comes to factory ECUs, there’s the fact of how they’re coded along with the physics of engine control, and then there’s guesses. I spent years guessing until I got to look behind the curtain. Now, all I can do is shake my head at what’s being shared out there.

This is really getting off topic. I am glad to be taken to school. In fact I welcome it! However, as you have pointed out before you are not willing to share.

[DSteck]

This is really getting off topic. I am glad to be taken to school. In fact I welcome it! However, as you have pointed out before you are not willing to share.

Correct, because my livelihood depends on it. Jake has been pretty forthcoming though.

[smokeshow]

Jake has been pretty forthcoming though.

I'm good now.

[Cringer]

Correct, because my livelihood depends on it. Jake has been pretty forthcoming though.

PM sent. Sorry for the thread hijack snives!

[GHuggins]

Anyway, not trying to contradict anyone in here and only stating what I've personally logged and seen, but in fact it's dialing in the VVE that is actually what throws the torque model way out. That combined with where the engine is now idling map and airmass wise.

Anyone can log delivered or engine torque on a stock engine vs one that's had the air models dialed in to see this big change. That and discussing with Jake and even one of Jake's old threads on here is why I went after the VE correction factor tool. It may not be correct, but it does really help to control throttle, which is primarily the map sides job. Nathan did a great job with this tool and it is how "I" wanted it, so if it is wrong then it falls on how I wanted it designed I guess.

The DD tool coming out is not mine. Mike, another programmer is developing it. I'm only testing and reporting problems. Right now the E90's are not playing nice with it or it may just be user error or very plainly, something I'm doing wrong...

I do want to know how logging and correcting the torque models turn out as I'm more interested in the side players and how they'll affect things.

[DSteck]

The proper sequence of events is to dial in the airflow itself (MAF and VE), then do torque models. The APC torque model is going to be influenced by the VVE, so that's why tweaking VVE will impact it.

Steady state on a dyno will be your friend.

[GHuggins]

^^^ Yes, this is what I and everyone in this thread as far as that goes believe too I discuss a lot of things with Jason and have seen quite a few of his cals via those discussions. I know he's in the top for dialing things in, especially for keeping things OE like with all the power and longevity benefits. Same I strive for. We just don't always agree on the map side of the torque model is all Wish someone would hand us the keys to the chest so to speak, but instead we have to test and dig for everything. Keep us updated...

On a side note Say one were to want torque models for specific common cams with usual minor mods such as what most do to their vehicles (CAI and LT's for example) how much would you charge for them?

[DSteck]

Probably about ten grand.

[snives]

heheh, I don't mind the hijacked thread as long as people are happy contributing. I do really appreciate the amount of knowledge that is distributed around the country in all of your heads. I totally agree with tuning being 100% science, but when you don't have the ECM code, that's when tuning becomes more of a religion and people rely on anecdotal evidence and hivemind beliefs. I am a software engineer, and do happen to know how to do regressions, neural networks, PID feedback loops even know a little bit about cars but I don't know the GM ECM operating system code, so I am trying to learn just like everyone else. Anyways, you are all appreciated for your help! (getting back on track)

TriPinTaZ said something interesting, "You always want Zero Pedal Torque around ~0 so that it has room to add/remove torque for the A/C, alternator load, power steering pump(in some cases) or when you put it in gear for Automatic Transmission cars"

If that is true then could I log Engine Torque - ZPET and to backfill the torque tables? Doing so should end up offsetting the base torque table by the ZPET, and when running should produce a ~0 ZPET, if I'm thinking straight.

[GHuggins]

It'll most likely have you running in circles doing it that way cause once you remove from different cells it'll change the commands and jump to a different torque via the throttle command that the third module is looking at. We got into a long discussion in the throttle oscillation thread. Got it sidetracked too More detail of what everything actually is in there or I guess somewhat more as to how it works.

[TriPinTaZ]

heheh, I don't mind the hijacked thread as long as people are happy contributing. I do really appreciate the amount of knowledge that is distributed around the country in all of your heads. I totally agree with tuning being 100% science, but when you don't have the ECM code, that's when tuning becomes more of a religion and people rely on anecdotal evidence and hivemind beliefs. I am a software engineer, and do happen to know how to do regressions, neural networks, PID feedback loops even know a little bit about cars but I don't know the GM ECM operating system code, so I am trying to learn just like everyone else. Anyways, you are all appreciated for your help! (getting back on track)

TriPinTaZ said something interesting, "You always want Zero Pedal Torque around ~0 so that it has room to add/remove torque for the A/C, alternator load, power steering pump(in some cases) or when you put it in gear for Automatic Transmission cars"

If that is true then could I log Engine Torque - ZPET and to backfill the torque tables? Doing so should end up offsetting the base torque table by the ZPET, and when running should produce a ~0 ZPET, if I'm thinking straight.

I don't actually do anything fancy with logging zero pedal engine torque. I just use it as a reference to make sure I don't have the torque model, Airflow or VVE too far off. This value is a good indicator if you have idle rigged to try and behave by lying to the ECU about the actual airflow or torque. Along with a table or two that isn't defined by HPTuners, keep in mind that Airmass = Torque. More airmass, more torque. Less airmass, less torque. Then you have VVE/MAP, same thing applies. And lastly you have Virtual Torque which "roughly" outputs what the ECU THINKS the torque is. And we haven't even gotten to the torque coefficients yet. There are a ton of tables not defined by HPT either. I've been fortunate enough to know someone that can fine these parameters and I use The User Defined function in HPT. Anyway, my point is, you can't skew one of the tables to make the ECU try and behave like they used to teach 6 or 7 years ago, you have to make them all play nice if you want a car that drives properly.

[smokeshow]

Zero pedal torque should be pretty close to zero...but adjusting just any ol torque calibration to get it there isn't really accounting for the source of the error. If you change engine friction, get a looser torque converter, or even just have significant error in your torque reserve, zero pedal torque will reflect it. But that doesn't necessarily mean 50Nm reported from ZPT is actually the excess at the crankshaft. So changing a torque model to drive it to zero could be the totally wrong direction to go.