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Thread: Where does MAX TRQ come from?

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    Tuner MakesBadDecisions's Avatar
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    Where does MAX TRQ come from?

    If max torque is limiting? Where does it come from. Example. 2017 - L86 TSPv2, CAI, LTH no cats, tuned ECM and A8 TCM.

    In the screenshot of a pull MAX torque is lower than actual and predicted, shouldn't there be some limiting?

    Log attached, will share tune privately if needed.

    I see some of you have figured out a mathematical ways of editing VTrq tables. I am very curious as I have yet to find a repeatable and reliable way of making changes based on some sort of error math. I feel as though we are missing lots of tables in the editor, like the example of the missing injector temp tables found for GEN4.

    Not looking for a handout just helpful insight with maybe some data inspired fact.

    Thank you and have a great Easter.
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    Last edited by MakesBadDecisions; 04-21-2019 at 02:19 PM.

  2. #2
    I've been searching for the answers on all the torques as well. Its the most confusing thing ever with all the torque PIDs there are and none of them have any sort of logical correlation to them either. Sorry I can't help but hopefully we can figure it out. The people who have figured it out I feel have just found with trial and error, and without your own personal engine dyno and proving grounds having to do that much trial and error is a nightmare and would probably drive you insane.

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    Tuner MakesBadDecisions's Avatar
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    Exactly and I agree 100%.

    The web of information and data is confusing at best. Most, me included, have lied enough to the ECMs to get the results wanted. Unfortunately I believe at this point we are lacking the tools and data needed to mathematically make changes. I dont mind cause and effect but at what point, like you said, do you go insane. I use complicated math and filters to provide the best end result possible. Not making changes based on data proven math is driving me insane.

    Look at an E92 file and vast idle tables compared to the E92A. There are hardly any tables for idle in the E92A. So that leaves jacking the reserve and ext load table around to get the TB to open and timing to stay above what ever you might have in the minimum spark table. Yet you can go into the Virtual TRQ tables and monkey around all over without a direct cause and effect, like getting the TB to open more and timing to stay above your minimum table. \

    Some one can correct me if I am off base as I am willing to change perspectives in order to gain a better knowledge base for how this TRQ based system works.

  4. #4
    We are definitely missing tables. A good example is idle timing. My 17' 1LE stock idled around 2-3 degrees hot. Another 17' 2ss I tuned recently idled at 14-15 degrees when it was stock. The only difference I found between the two stock tunes was the external load table. I copied the 2ss table to my 1LE table. Still idled at 2-3 degrees. Same year, same values throughout both tunes, both cars bone stock, yet a 12 degree difference in idle timing.

    All other 1LE's I've tuned idle 2-3 degrees stock. While stock 1ss and 2ss cars all idle in the teens stock. The only way I have found to bring the idle timing up on the 1LE's is cut the torque in half or more in the vtt -10 and 0 degree tables in the idle rpm, and airmass/map cells. Makes no sense with what we have so far. Sometimes it seems like cranking the virtual torque like that to achieve a result is a band aid.

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    Tuner MakesBadDecisions's Avatar
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    Agreed 32vape, thanks for the input. My 17' L86 idled stock between -6 and 5, cold to warm. With the TSPv2 in it, I had to cut huge chunks from the VTRQ, just like you mentioned. Band aid is correct, keep pulling from those areas until desired results are achieved.

    There are many many smart people in this forum and those that know will probably never speak up.

    Like most of you I have put the time in, from GEN3 to current. Those that just started tuning and started with GEN5 are crazy. I look forward to GEN3 and GEN4 for tunes, setup the scanner and copy and paste error, so simple it is almost mindless at times.

  6. #6
    Senior Tuner Higgs Boson's Avatar
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    Have you tuned your maf AND VVE tables in every cell possible to exactly 0% error?

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    Higgs,
    MAF and VVE are within 3%. Its amazing how things line up once that part is done. I have tried for the perfect 0% error, one day its 0.2% error and next its 3 or 4% error. I live at 4800 feet, and lately the baro KPA has been swinging up to 4kpa as weather systems are moving in and out.

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  9. #9
    Senior Tuner Higgs Boson's Avatar
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    I run stock VVT, Peak Torque, and Driver Demand on my whipple/cam Z06 with port injection. No limiting.....

    Are you having an issue with something or just wondering why you don't have any limiting when Max Tq is lower than actual?

  10. #10
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    I have read that about your setup and most of the time that is is how most of the cars end up working the best. But, when you introduce radical cams, as I assume with a blower your cam is not that rowdy, different intake manifolds, throttle bodies, etc. You cant just leave the VTrq, peak, and DD tables alone and you are forced to monkey around in the VTrq tables as things are now so far from stock.

    I am using the MAXTrq as an example of not following the rules. With the E78 and the guide provided for that we were given the basic architecture of how this system works. If the MAXTrq, in my case, does not limit things then what other parts of the inner workings do we have wrong. I know things have progressed greatly since then but the similarities are there.

    Since the truck was new I noticed the MAXTRQ was not limiting and I wrote it off as part of the truck OS that may not follow those rules, as the table for the truck is maxed out at 6042 from stock. Even stock it idled weird, had surging issue at times, stalled randomly all within the first 5k of owning. I did nothing but log for the first 5k as the 17' was different than the 14', just by enough there was a learning curve. After cleaning up the MAF and VVE tables most of those issues went away or were barely noticeable.

    Like 32vape said, you sometimes have to lower torque in the VTrq tables to get idle spark up. Down side is sometimes it introduces flaring and other random weird stuff. Just my observations.

    I am more so trying to understand what rules apply and don't apply when it comes the VTrq tables and how they work, or don't work, together.

    Is there a true mathematical way to edit the VTrq tables with the tools we have within the software? Even add the tool like a dyno, which I have, is there still a way?

    Which table is looked at for predicted or how are they weighted if looked at both?

    How are the tables weighted out when producing your actual torque number, according to the scanner channel?

    What does the external load table truly model and how does it affect things like commanded throttle opening and spark torque mangement?

    I understand the spark is for immediate torque control as throttle is for long term control, but what controls them?

    I really thought I had a solid grasp on this but these questions keep coming up as blindly changing things drives me nuts. This is all math and math should be used to make changes.
    Last edited by MakesBadDecisions; 04-22-2019 at 04:31 PM.

  11. #11
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by MakesBadDecisions View Post
    I have read that about your setup and most of the time that is is how most of the cars end up working the best. But, when you introduce radical cams, as I assume with a blower your cam is not that rowdy, different intake manifolds, throttle bodies, etc. You cant just leave the VTrq, peak, and DD tables alone and you are forced to monkey around in the VTrq tables as things are now so far from stock.

    I am using the MAXTrq as an example of not following the rules. With the E78 and the guide provided for that we were given the basic architecture of how this system works. If the MAXTrq, in my case, does not limit things then what other parts of the inner workings do we have wrong. I know things have progressed greatly since then but the similarities are there.

    Since the truck was new I noticed the MAXTRQ was not limiting and I wrote it off as part of the truck OS that may not follow those rules, as the table for the truck is maxed out at 6042 from stock. Even stock it idled weird, had surging issue at times, stalled randomly all within the first 5k of owning. I did nothing but log for the first 5k as the 17' was different than the 14', just by enough there was a learning curve.

    Like 32vape said, you sometimes have to lower torque in the VTrq tables to get idle spark up. Down side is sometimes it introduces flaring and other random weird stuff. Just my observations.

    I am more so trying to understand what rules apply and don't apply when it comes the VTrq tables and how they work, or don't work, together.

    Is there a true mathematical way to edit the VTrq tables with the tools we have within the software? Even add the tool like a dyno, which I have, is there still a way?

    Which table is looked at for predicted or how are they weighted if looked at both?

    How are the tables weighted out when producing your actual torque number, according to the scanner channel?

    What does the external load table truly model and how does it affect things like commanded throttle opening and spark torque mangement?

    I understand the spark is for immediate torque control as throttle is for long term control, but what controls them?

    I really thought I had a solid grasp on this but these questions keep coming up as blindly changing things drives me nuts. This is all math and math should be used to make changes.
    cam specs are around 236/244 on a 114 I believe. I have a NW 103 TB and a different roots blower so....

    external load models the zero pedal torque so I just logged that into the ext load table for a while and copied in and it works great for me.

  12. #12
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    Higgs, thanks for taking the time to add this discussion. I assume those are 0.050 specs, ok a little rowdy, point made.

    What is your commanded idle? Where does your throttle and spark sit at idle cold and warm? Automatic or manual? Just trying to understand.

  13. #13
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by MakesBadDecisions View Post
    Higgs, thanks for taking the time to add this discussion. I assume those are 0.050 specs, ok a little rowdy, point made.

    What is your commanded idle? Where does your throttle and spark sit at idle cold and warm? Automatic or manual? Just trying to understand.
    right now 800, but i do like 850 also.

    the NW103 i believe sits at 16% or so with about 10 degrees of spark lead.

    manual

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    Thank you for that. What are your feelings on the reserve table and how it interacts with things?

    I know this is starting to stray from original post but I wanted to start the discussion about the whole torque based concept and that example was what I had at the moment. Now we are talking idle which is great because that is a huge part of the web of data.

    I can say that the TSPv2 in my L86, just finished it up Saturday, with appropriate changes to both air models, base idle, startup air, startup rpm, external load and reserve tables only. It idles well at 700 spark 8-10 and TB at 14-15, very little chop and stable. The big thing i noticed is how the trans shifts. Same tune for the TCM and it shifts so different, actually way better. Not only the WOT shifts but part throttle as well. All torque management retained and fully active. Trans shifts are crisp, clean, no push feelings and FAST. I spent months getting the trans to behave the way I wanted so I was surprised, pleasantly, by how it was behaving. I do have some work on decel shifts and the new coasting cruise feeling, need to visit the DD tables for that. I spent a lot of time getting just a little cruise feeling at freeway speeds and more engine decel under 55. Did that for no reason other than because I wanted to see cause and affect.

    SO.. that brings me back to the VTrq tables, as obviously the new cam changes the entire air and torque models. After re-mapping the air models the result is higher torque delivered therefore transmission is using higher portions of the tables. Vice versa with the decel areas of the tables used, as now i have a little more harsh coasting down shift and the cruise feeling. It also makes sense that the new cruise feeling is that the requested negative torque, didnt change my DD, no longer is requesting enough negative torque to allow for more decel because this cam produces more torque than the stock cam at the airmass/map/rpm value. Or this thinking completely wrong?

    So instead of making changes to the VTrq tables I am going to visit the DD table and request more negative torque. The reason is I know if i monkey around with the DD table I will get the result I want with minimal side effects. Or do I monkey around in the VTrq tables to see cause and effect. That is the dilemma I have.

    I makes more sense to be able to command a value and expect a result, the actual, and use our maths to work out the percent of error and apply appropriately. I see no way to do that with the VTrq tables. Does any of that make sense?

  15. #15
    Senior Tuner Higgs Boson's Avatar
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    I have heard of some people applying the same % correction to the VTT as they needed to apply to the VE/MAF (so you would want to log fueling error to the VVT table and compare vs your stock airflow tables now that you've already changed from stock).

    I sort of think that the VTT needs changing just for auto shifting, maybe manuals just don't use it (although if you change it there are changes to operation, just always seems worse though unless you can change everything in proper conjunction, which we really can't).

    I have found the reserve table does nothing. external load table definitely affects idle and closed throttle decel, has a sort of throttle cracker/follower effect

    what does your VVE table look like?

  16. #16
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    It makes sense to apply the airflow error to the VTT, as the relationship of airflow and torque go hand in hand. I think you would have to wait until both air flow models are dialed and then use some creative math, filters and external spreadsheet to then apply the error % between stock and new air models to the VTT. Sounds like a convoluted and inefficient way of doing it with way too many error variables. I could very well be wrong on that entirely.

    Yes, you finally said it. (although if you change it there are changes to operation, just always seems worse though unless you can change everything in proper conjunction, which we really can't). Thank you as I agree 100%.

    Because if you hack the VTT you may get your desired result, but that has unwanted consequences else were. Like when you cut torque out of the idle areas and you get throttle opening and high rpms on park to reverse/drive shifts. Because the VTT is HP's visual interpretation of the math from the OEM. We can't take it as 100% true and even with the smallest of changes in the smallest of areas has wide spread consequences and the error increases exponentially the further you get from the table in the chain of commands.

    VVE also visual interpretation of an equation. My VVE is nice and parachute shaped, as nice and shapely as you can get with limited curve direction based on zone size and the obvious interpolate into no mans land. I do not change boundaries as I like to carry continuity from one tune to the next, one less thing to have to remember. My VVE error runs -5 to +2 compared to my math for VVE airflow error. My MAF this morning was -3 to +1 across the board.

    For now instead of playing around in the VTT, I will stick with playing with the modifiers based on torque. Instant results with very minimal external consequences. My opinion of course.

    Again, thank you Higgs for your perspective.

    I DO NOT want to turn this thread into a pissing match. I want perspectives from those that have, or think you have the torque based systems figured out .

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    This is a great thread. I am one of the crazy people learning to tune on GenV stuff.. pretty challenging..

    Most people point out that Max Torque is not a limit, but it is still a problem. I just noticed on my logs that whenever DD engine torque goes above MaxTRQ the throttle blade opens to 100%. This makes actual Maf and Map go way above driver demand and makes the trans shift like crap. I notice in your log picture it does the same thing, you can see the Blade % get ahead of the Pedal % when you cross over MaxTRQ.
    I have been chasing this bad shifting problem for a long time, but it seems that it wont be fixed until I can raise Max TRQ.

  18. #18
    Tuner MakesBadDecisions's Avatar
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    What is the vehicle? Just for a reference point.

    I will pay more attention to the crossover and blade movement, as I cant say Ive put that together. Good catch, thanks. I cant say i have shifting problems based on those circumstances as my truck OS does not follow MAXTrq in any way I can reproduce. Tables were maxed from the factory, if in fact that is were MAXtrq comes from. I log only the actual torque channel from the TCM as the TCM only looks at actual torque for its calcs, from what I can see. I logged the ECM and TCM actual channels for a while and they were the same 100% of the time. I did that until I needed a spot for another channel, so the ECM channel went away leaving only the TCM produced channel. Until we know for sure where the MAXTrq comes from it is any ones guess to its affects. I have seen it limit and seen it not limit, sometimes it follows just under Peak sometimes it does what ever it feels like. One could equate it to a women, moody and unpredictable results from testing.

    I spent a lot of time in the DD tables getting the blade to follow the pedal and not "flare", I have not got that far yet as I am still working on other parts of the tune after cam swap. I found the engine "felt" better, shifted more predictably and shifted better the smoother and accurate the table was. Because my DD tables references rear axle torque, request in the top of the table is 6600ft/lb, is was almost impossible to plot every shift point, pedal% and blade% against the table to make anything useful. Because the engine torque requested changes based on DD I had to settle with a "flare" of throttle on gear change. That flare comes from requested torque not changing as the gear changed, until DD decreases the throttle will remain open until the requested and delivered cross again, so back out of pedal or allow engine speed to increase until that cross over point. Logged and tested this more times than I want to admit. I tried putting break points in the DD table based on shift points using a spreadsheet to calc the shift point and actual torque logged multiplied by gearing to produce a DD ft/lb, it was a "bucking" nightmare. I was able to minimize the "flare" affect, but only to a point. Once I got a point that the pedal and blade were in harmony I no longer touch it and move on to trans "feel". I have a rock solid trans tune that I made changes to before and during but mostly after I got throttle to closely follow pedal. If the shift was to harsh/soft or fast/slow i would look that area up in the inertia and timing tables but mostly in the pressure tables. Make changes based on the "feel" and data, push it up or push it down. I am a firm believer that smooth tables produce smooth results.

    What I have learned about DD and is open for debate:

    The DD table needs to represent what you as the driver want. I have seen tables with a cliff at the end and just unrealistic numbers, but drive ok, with and without throttle limiting. But once I play around in there and request realistic numbers and smooth things out differences are immediate and the vehicles typically become smoother and more predictable. I like to use my pedal and my DD represents that as I have lots of fine control in the bottom 60% of the pedal and then it ramps up and gets aggressive. There is some sort of tension spot in my pedal out there around 70% or so, cant think of actual at the moment, that is were I made the DD table use that as my "shit and get" point. So if I want WOT and power down shifts I really have to ask for it. In my opinion this has lead to a smoother operating vehicle from request to delivered, engine power to shift quality.
    Last edited by MakesBadDecisions; 04-24-2019 at 05:10 PM.

  19. #19
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    Virtual Torque and Driver Demand functionally use the same logic on a manual trans car and an automatic trans car. However, the automatic trans references torque values to determine how to shift so it is more of a requirement to have the Torque Model in line on Automatic trans cars.

    To Higgs point though, even with an Auto I would set VTT and DD to stock values, tune the MAF and VVE, and then adjust the Torque Model if needed. If the car is shifting properly and not limiting, I wouldn't bother even touching VTT or DD. Or you might find that you just need to bump up the DD tables in the high load areas to request enough torque to keep the trans shifting firmly/fast at full throttle.

    Max torque is the "logical" value output by the ECU based on a complex formula(that can actually be found on this forum). If you change the way the engine flows air, change VVE/MAF etc, this will change the value output by the formula since the before mentioned values are main components used in this calculation.
    Last edited by TriPinTaZ; 04-24-2019 at 07:29 PM.
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  20. #20
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    Thank you TriPinTaZ for adding to this conversation as you have been a huge help in other posts. I spent last night looking for the formula and struck out, only have a couple hours a night of alone nerd time and get up at 0430. I have most of the important threads bookmarked and re-read those and still could not find the equation. I thought had read about every GEN5 post and even some Ford threads, which were extremely helpful in understanding the concept and theory, and never came across an equation. I will keep looking as I only re-read bookmarks, tonight begins the el'google searching.

    I agree with and understand everything in your comment except one part of DD, not being argumentative. Just asking questions.

    Does or does not the top of the DD need to request 100% producible torque and not allow TM to limit throttle and/or timing? Am I wrong in that overly simplified statement?
    How does DD affect transmission shifting?
    Does the TCM not look at delivered/actual torque as the look up reference for timing, pressure, inertia,etc?
    Just like the 4spd trans, dont we go into the proper tables and bump some pressures, slide some inertia around and speed things up to make the trans shift firmer and faster than stock?

    My statement about adjusting the DD for "flare" was just about adjusting the requested torque to suite each person based on pedal position. I found the truck stock wanted to go full throttle at the strangest points and fine control was not to my liking. I spent a while knocking the low to top rows down until limiting started, then pushed the top rows back up until limiting went away. Smoothed and manually adjusted between low parts of the table and the top. It was pretty amazing how aggressive the top parts of the table were. Dont get me wrong I like to rip around like anyone else but it was in my opinion annoying. Since I had to tools and time I played with it to see cause and affect.

    In the end, DD should represent Driver Demand and in my case Driver Demand is rear axle torque and rear axle torque comes from engine torque multiplied by gearing and other factors. Once the axle torque is requested it is up to the TM logic to achieve the torque by whatever means it deems necessary to achieve or not achieve based on demand and limiting factors. Is that a correct statement?