Lets Talk Torque Modelling / Virtual Torque

[hjtrbo]

Also with the cold starts I can see if your minimum air multiplier needs a massage as a separate thing...

Could be completely ok

[Allen Vos]

Dyno is king, but can get close just for idle without it. Your WOT and general drive torque areas would not get any work based on just a mild cam swap if it came to me for a tune. Greg would probably dial it though .

In the case you were auto and adding forced induction, that is a WHOLE different scenario. As stated by Greg, the ECM torque reading would need to be checked against the readings from a good high end dyno. Or in leiu of that an experienced eye can know from the transmission line pressure if an increase to vtt is required. Any method all circles back to having spot on airflow data which is generated from a good tune formed from excellent injector / fuel system data.

Do 2 logs. About 8 minutes each from a bone cold start or until ECT has flattened.
Straight idle nothing else. A/C & climate fan off. Radio off. Lights off.
Probs will have to do it 24 hours apart.
Flash in your stock vtt tune the night before your first test.
After you shut the engine off following your first test, load in your mod vtt tune and let her sit till she's bone cold again, preferably the same time the next day.
Reason to flash the night before is to let any engine off timers run their course. Apples for apples testing method.
It can be done hot back to back, but better to be able to drive it so you can get injector tip temp down and let everything else settle down to nominals.
Also with the cold starts I can see if your minimum air multiplier needs a massage as a separate thing...

OK, so I have followed your instructions and have a couple logs here.

Attachment 142913Attachment 142914

Here are some screen shots of the Tables from the scanner.


Stock Virtual Torque Graphs, torque and spark
Attachment 142916
Attachment 142915

Modified Virtual Torque Graphs, torque and spark
Attachment 142917
Attachment 142918

Here is my tune with the modified Virtual Torque Tables.

Attachment 142919


So I am not exactly sure what we are looking for here to validate the changes to the Virtual Torque Air Mass Tables but what I did notice was the torque values in the graphs were a bit higher at idle on the modified torque table, however at 1000 rpm the stock table had a bit higher values.

I hope this makes sense to you and is a good indicator that we set things correctly.

[GHuggins]

https://patents.google.com/patent/CN100432404C/en

There's a lot more than this if you want to do some digging.

[hjtrbo]

wtf, Chinese?

[hjtrbo]

Looks ok to me. Maybe a tad high on modified log. Using the method I described earlier (the same one that you practiced), take 5% off the modified columns. Do another log, and this time right at the end, hold the revs at 2000rpm for 5 seconds then let the throttle go. Then once its stable again, give it a blip.

[GHuggins]

wtf, Chinese?

LOL, did you open it and hit the other languages button? It's in English I have the older GM patent somewhere too.


I think where he's messing up is with the "take this much % out". Multiplying the negatives by .9 or .95 or .8 or whatever is adding that much percent. He's adding torque instead of removing.


The patent was meant to show how the torque model references it's throttle and timing tables.....


He's also "blanket" logging torque. Needs to be broken up like this -

Torque Layout.jpg

Then if he has variable cam timing, break it up even more like this -

Torque Layout Variable Cam.jpg

[hjtrbo]

Sure thing.

[Allen Vos]

Looks ok to me. Maybe a tad high on modified log. Using the method I described earlier (the same one that you practiced), take 5% off the modified columns. Do another log, and this time right at the end, hold the revs at 2000rpm for 5 seconds then let the throttle go. Then once its stable again, give it a blip.

OK, so I don't have an issue relogging again, however based on what Greg is saying there is more torque added to the modified table using the method you described earlier.

I think what happened is we multiplied the top 3 numbers on the torque table which were negative by .9 when we should have multiplied it by 1.1 in order to reduce torque.

If we look at the values in the screen shots I've included you'll see at 700RPM and 200 MG of air flow the stock table shows 20. The table you modified for me shows 40. If you multiply the negative number's by 1.1 as opposed to .9, it reduces torque to 14.



Attachment 142934
Attachment 142935
Attachment 142936

Again I don't fully understand how this all works, but starting to get a general idea. I am assuming we want to see a bit less torque on the torque tables in the idle area so
lower numbers are better and I'm also assuming on the logs/graphs I want to see as lower torque numbers than stock?

I have no issue trying this but just want some confirmation this is the right way to look at things.

[Allen Vos]

LOL, did you open it and hit the other languages button? It's in English I have the older GM patent somewhere too.


I think where he's messing up is with the "take this much % out". Multiplying the negatives by .9 or .95 or .8 or whatever is adding that much percent. He's adding torque instead of removing.


The patent was meant to show how the torque model references it's throttle and timing tables.....


He's also "blanket" logging torque. Needs to be broken up like this -

Torque Layout.jpg

Then if he has variable cam timing, break it up even more like this -

Torque Layout Variable Cam.jpg

Thank you for pointing that out. Check out my previous post with the screen shots of the torque tables. I think you hit the nail on the head with multiplying negative numbers.

In order to reduce torque which I think is the idea here in order to reduce a negative number by 10% it needs to be multiplied by 1.1 as opposed to .9.


My question for you is when you say I am blanket logging torque I need to do it the way you showed in your screen shot

I'm a bit confused as Nathan was telling me to do everything on air mass torque tables and what you had said points to the MAP based torque tables.

I know I need to address the MAP based torque tables after the airmass tables because my idle now sits at 57 KPA vs the stock at 33 KPA.

Feeling a bit lost here as I'm told to try and do different things that may or may not be relevant to each other. lol

[GHuggins]

They have to be balanced. That's the point of the multiple tables.

If you looked at the patent and then know that the map side is "primarily" used for throttle control, you would see that the map side directly relates to throttle as it's primary lookup as it directly relates to it's "desired position for idle" - if this is the correct patent "I'll have to double check", then it clearly states that the map "value" is referenced first to define desired throttle based off of desired eff throttle area - that then defines the torque and timing lookup for idle that is referenced on the airmass side - this is where the airmass side then plays into it. It's just as much from the airmass side as the two relate to one another, SO they must be balanced or close to it..... Lowering airmass to bring things in line does indeed work, BUT you're usually skewing the airmass side when you're doing that (making it do ALL of the work and leaving the throttle desired locked where it was, which can cause its own problems) Now, adjusting your VE table does bring the map side back in range - this is why there are those who say you don't need to adjust anything. However doing this doesn't put it back right.

Your torque goal is around 10 to 40 lbft at idle. 4th gens are fortunate enough to not have full torque control. You have other tables playing into it that you can "usually use" in place of the torque models. However there are those oddball builds that will want to idle on negative ignition timing even on gen 4's because things changed so much and tuning in the torque model will make a difference even with your more minor mods, however....

Fuel needs to be completely right, before messing with any of this and I'm not just talking about select areas of the VE tables, but all of it.

Guess it doesn't hurt to change stuff just to see what it does, but this needs to be dialed in last on one of these.

[hjtrbo]

Word

[Allen Vos]

They have to be balanced. That's the point of the multiple tables.

If you looked at the patent and then know that the map side is "primarily" used for throttle control, you would see that the map side directly relates to throttle as it's primary lookup as it directly relates to it's "desired position for idle" - if this is the correct patent "I'll have to double check", then it clearly states that the map "value" is referenced first to define desired throttle based off of desired eff throttle area - that then defines the torque and timing lookup for idle that is referenced on the airmass side - this is where the airmass side then plays into it. It's just as much from the airmass side as the two relate to one another, SO they must be balanced or close to it..... Lowering airmass to bring things in line does indeed work, BUT you're usually skewing the airmass side when you're doing that (making it do ALL of the work and leaving the throttle desired locked where it was, which can cause its own problems) Now, adjusting your VE table does bring the map side back in range - this is why there are those who say you don't need to adjust anything. However doing this doesn't put it back right.

Your torque goal is around 10 to 40 lbft at idle. 4th gens are fortunate enough to not have full torque control. You have other tables playing into it that you can "usually use" in place of the torque models. However there are those oddball builds that will want to idle on negative ignition timing even on gen 4's because things changed so much and tuning in the torque model will make a difference even with your more minor mods, however....

Fuel needs to be completely right, before messing with any of this and I'm not just talking about select areas of the VE tables, but all of it.

Guess it doesn't hurt to change stuff just to see what it does, but this needs to be dialed in last on one of these.

Thank you for that. Its nice to finally have that 10-40 ft pounds at idle spec, so now I at least know what I am shooting for.

I briefly read that link you posted on the torque control patent but will sit down this weekend and read it through thoroughly. But I do understand the basics of what's being said.

Now when you say balancing, just to clarify here is what I am interpreting this as.


When I log with the scanner, I would want to see the same torque readings in my Virtual Torque graphs at idle on both air mass and MAP tables?

And of course adjust both MAP and Airmass tables to match each other and reflect the appropriate torque spec you provided?


So after all this my stock air mass log showed 33 foot pounds of torque which falls within your spec so I'm assuming the stock airmass tables are sufficient on mine?

Are you better to stay to the high end of your spec or the low end?


With regards to the spark logging, my idle spark was very close to the 18 degrees base idle timing in the logs.

If torque is ok or within the 10-40 ft pounds, can we assume spark is ok, or are there more settings that need to be changed on the spark side?


I get fueling needs to be spot on in all areas, however does it hurt to dial it in a bit closer because of the cam swap then get it a bit closer once I get driving the car and have a more complete VE table?

Again, I am just playing with things right now and always save the previous tune incase the changes I make don't work so I can back the train up if needs be.

[Allen Vos]

LOL, did you open it and hit the other languages button? It's in English I have the older GM patent somewhere too.


I think where he's messing up is with the "take this much % out". Multiplying the negatives by .9 or .95 or .8 or whatever is adding that much percent. He's adding torque instead of removing.


The patent was meant to show how the torque model references it's throttle and timing tables.....


He's also "blanket" logging torque. Needs to be broken up like this -

Torque Layout.jpg

Then if he has variable cam timing, break it up even more like this -

Torque Layout Variable Cam.jpg

Greg, would you be willing to share your scanner graph file of all the individual virtual torque tables?

I would like to see how you broke them down and how you set up the filters for spark on the tables.

[GHuggins]

To be 100% honest this will help balance the models to one another, but it's not 100% precise. You catch "glimpses" of reported differences as long as you log right after flashing a new file, but as we discussed the models will learn and shift, so you do a long log and all of a sudden everything will match even though it really doesn't...

For your basic graphs - this is only separating based off of spark - 20 degree spark shown -
[14.161] > 15 and [14.161] < 25

For the ones looking at the moving cam - again 20 degrees spark shown - looking at 7 degree cam position -
[14.161] > 15 and [14.161] < 25 and [2172.161] > 4 and [2172.161] < 11

There's probably a lot better way to do this. I go up through 15 degrees of cam movement. I don't use them anymore for anything other than making sure the models are close as I'm using a different method to dial the models in now.

[Allen Vos]

To be 100% honest this will help balance the models to one another, but it's not 100% precise. You catch "glimpses" of reported differences as long as you log right after flashing a new file, but as we discussed the models will learn and shift, so you do a long log and all of a sudden everything will match even though it really doesn't...

For your basic graphs - this is only separating based off of spark - 20 degree spark shown -
[14.161] > 15 and [14.161] < 25

For the ones looking at the moving cam - again 20 degrees spark shown - looking at 7 degree cam position -
[14.161] > 15 and [14.161] < 25 and [2172.161] > 4 and [2172.161] < 11

There's probably a lot better way to do this. I go up through 15 degrees of cam movement. I don't use them anymore for anything other than making sure the models are close as I'm using a different method to dial the models in now.

So is each Virtual Torque Spark table is plus and minus 5 degrees of spark based on the Virtual Torques Spark tables number?

I have to be honest I thought it was this way

Spark -10 - -10 to 0 degrees
Spark 0 - 0 - 10 degrees
Spark 10 - 10 - 20 degrees
Spark 20 - 20-30 degrees
Spark 30 - 30 - 40 degrees
Spark 40 - 40 - 50 degrees

I have an LS3 so I don't have to deal with variable the Cam stuff

[GHuggins]

You can break the torque models up however you pretty much want. So, if you want to go by 2 or 3 degree increments, you can or if you want to divide up the airmass into finer resolution you can to a degree or whatever. All of those settings are on the left side of the torque models.

I just break it up like I do for logging.

[Allen Vos]

You can break the torque models up however you pretty much want. So, if you want to go by 2 or 3 degree increments, you can or if you want to divide up the airmass into finer resolution you can to a degree or whatever. All of those settings are on the left side of the torque models.

I just break it up like I do for logging.

I see that you can set your min / max spark and the number of increments or degrees per table as shown in the "Spark Iterations" area

Here's a pic of my Virtual Torque Tables

Attachment 143065

So here is where the confusion is for me.

Min Spark is -10
Max Spark is 40
Increment is set to 10

So that's a swing of 50 degrees of spark with 10 degrees(Increment) per table.

In my eyes that's only 5 tables. Yet there are 6 tables

I realize I can set it however I want but how am I supposed to figure out what degrees of spark are for each table? I would need to know that to log each table

If you look at the pic I wrote the spark degrees that I think is there, however it would go to 50 degrees and 40 is listed as the max.

Can you see why its confusing?

[GHuggins]

The tables are always in the middle of the timing degrees, not the beginning, so plus/minus 5 degrees for them. That's how most of the stuff in the cals works out when you're logging them such as multipliers based on temperatures. You can go by plus/minus 4 from target to be more precise. Plus I think your forgetting to count the 0 table - that's -10, 0 , 10, 20, 30 and 40 for a current total of 6 tables. Now if you really want to go crazy with it, you can define up to 101 different tables depending on how much you break it down per model

[Allen Vos]

The tables are always in the middle of the timing degrees, not the beginning, so plus/minus 5 degrees for them. That's how most of the stuff in the cals works out when you're logging them such as multipliers based on temperatures. You can go by plus/minus 4 from target to be more precise. Plus I think your forgetting to count the 0 table - that's -10, 0 , 10, 20, 30 and 40 for a current total of 6 tables. Now if you really want to go crazy with it, you can define up to 101 different tables depending on how much you break it down per model

Like this?

Spark(-10) (-15) to (-5) degrees
Spark 0 - (-5) to 5 degrees
Spark 10- 5 to 15 degrees
Spark 20 - 15 to 25 degrees
Spark 30 - 25 to 35 degrees
Spark 40 - 35 to 45 degrees

[GHuggins]

yes.