Any idea what the torque demand numbers mean?

I'll give you the short version: I have been experimenting with the driver demand torque tables and the numbers are confusing. HPT says they are axle or engine torque depending on the application but on a stock Buick GS, the highest number is 215 and that is much lower than engine or axle torque. The bottom numbers are -11, how can it be negative torque? As an experiment I set the whole table to 10 and the throttle was totally dead but the idle would go up with speed and wouldn't come back down until the car stopped moving. Any ideas what the numbers mean?
https://i.imgur.com/AP9B42m.png

That table basically tells the engine how much power you are requesting and throttle control ... setting it to high in the lower pedal regions will make the throttle uncontrollable and setting it too low will kill the power because its limiting the ecm ... you mostly just want to raise the settings in the upper end like from 70% and up ... maybe increase the mid section a little to help with part throttle but again dont get carried away

Yes, I understand what the table basically does but If I am going to create a perfect table for my use, I need specifics. I need to know what exactly the numbers mean and what they relate to. Here is a map I use in dry conditions
https://i.imgur.com/Rxkdvov.png

before you open the table hover over its access button with your mouse. bellow a description will appear for that table. HPTuners always puts the table limits in there and units. If the units are not there (like ve table units dont exist for lsj or gen3 ls ecu's) then the values are deemed to be unit-less placeholders.

it may be one of those things your going to have to accept as having unknown dimensions or unknown reference sensors. Welcome to coefficient based tuning...it pisses a lot of people off because of shit like this.

Though they're for LNF's, it's worth reading these previous threads on optimum spark tables to get am understanding of how torque based ecu's use what I call "urgency tables".

They are higher in terms of their ability to supercede other tables. Their absolute values are not as important as are their relative values.

It's also very important to note that setting a value in a cell to its maximum possible value in a torque based ecu will cause a non-linear response. In other words, if the available scale is from -100 to +1000000, once you exceed the ecu's understood linear responses to achieve your request it reacts with an exponential response since it can't achieve the relative scale change rapidly enough. This results in runaway WOT situations.

I have tested this extensively with many tables with the understanding of what could occur and what to do if it did occur. If you don't have another reference table which supercedes the one you are modifying in authority for final output and you set that table to maximum value you can end up in a runaway engine scenario.

https://forum.hptuners.com/showthrea...-tables-how-to

https://forum.hptuners.com/showthrea...K-Really-Works

Quote:

---

Originally Posted by cobaltssoverbooster

before you open the table hover over its access button with your mouse. bellow a description will appear for that table. HPTuners always puts the table limits in there and units. If the units are not there (like ve table units dont exist for lsj or gen3 ls ecu's) then the values are deemed to be unit-less placeholders.

it may be one of those things your going to have to accept as having unknown dimensions or unknown reference sensors. Welcome to coefficient based tuning...it pisses a lot of people off because of shit like this.

---

Yes, I addressed this in my first post. HPTuners says it is engine or axle torque depending on application but it is clearly not either of these things. It looks like I'll just have to experiment to figure this out.

it could be calculated torque. values higher produce no resistance to output. lower values that are within the range of the actual calculated torque could produce a restrictive output result. therefore anything set super high would produce a full power output without interference.
it acts as a torque demand request which makes perfect sense.

i only made my general comment about no units because i didnt have access to a file i could open and verify what they put as units. remember the values will seem high because its a calculation not a direct measurement of torque.

I think this table is overlooked a little, at least in terms of vehicle performance. I have tried dozens of different settings for this table and you are correct that too high of numbers down low produces an almost uncontrollable car. That first table I posted is what I used in the torrential downpour at the SCCA Solo Nationals last week and it made for a very easy to drive car. The second table is what I ran when it dried out the next day and it had the punch I needed. My wife in the rain and me in the dry
https://i.imgur.com/vWQr9ei.jpg
https://i.imgur.com/TT6EmLk.jpg

nice car!

Quote:

---

Originally Posted by cobaltssoverbooster

nice car!

---

Thanks. I finished 3rd and my wife was 6th

It was fun to watch. Couldn't quite make up for the rainy day 1 that mixed up a lot of classes.

I was told that in the driver demand table on the LTG e39A ecm it is in kW of power Makes sense. In the 2016 newer LTG it is in axle TQ

Quote:

---

Originally Posted by raflyer

I was told that in the driver demand table on the LTG e39A ecm it is in kW of power Makes sense. In the 2016 newer LTG it is in axle TQ

---

I think I finally have an answer-Thank You!! Although, come to think of it, Kw is another way of measuring horsepower, not torque. Now, why are some numbers negative?

Ok, maybe this is a stretch but hear me out. The top number on the torque table for the 2012 Buick Regal GS is 215. If this is torque in kg/m it works out to 1555 ft/lbs. If the 215 is supposed to be torque at the axle, and you take the torque multiplication of a Regal GS in 1st gear, suddenly that 1555 ft/lbs seems entirely reasonable and the math works.

torque in the metric system is N*m so it would be Kg*m^2/s^2 and in imperial it is lbf*ft
Torque (τ, Tau)= radius(m or ft) x Force (Newtons, Pounds Force)

if this table was N*m then 215 would equate to 156 lbf*ft
the conversion factor is .738 lbf*ft = 1 N*m

depending on the dyno graph output of a stock file which im assuming makes closer to 215 at the axles, i would assume the table is axle torque in lbf*ft

Negative TQ is motored. Every time the wheels are spinning the engine the TQ is negative. You want to allow this to happen. For example, if you have zero tq at max engine speed and zero throttle it means the engine is still running in order to generate a net zero tq. You would basically be asking the engine to idle at 7000rpm.

Daniel

Can you explain this further? Does having negative numbers result in more engine braking when off the throttle? My throttle, even at idle is never lower than 22%, if I made all the cells below 22% negative numbers, would it try to drop the rpms every time I took my foot off the gas pedal?

trq engine - trq wheels = value table.

table value will only be negative when the deceleration value is less than the wheel torque.
if you have a hang issue then it could be commanding air to do what you experience now. its free to change, go test it if you can.

Quote:

---

Originally Posted by cobaltssoverbooster

trq engine - trq wheels = value table.

table value will only be negative when the deceleration value is less than the wheel torque.
if you have a hang issue then it could be commanding air to do what you experience now. its free to change, go test it if you can.

---

Are you sure about this? I'm still new to this, but engine vs. wheel tq will be gear dependent. If we ignore the trans/rear-end multiplication of TQ then really all we are talking about is the efficiency of these which doesn't seam important to me. In such a case I don't see how you would arrive at negative TQ. It seems more likely to me that these values are just engine.

If I'm right, then a more negative value will result in more engine braking. Negative TQ should just be the FMEP and PMEP of the engine (again, if my understanding is correct). The only parameter we can impact is PMEP by closing the throttle. The zero-fueling TQ will become more negative as engine speed increases due to FMEP. It would be interesting to know if anyone has figured out what this is because I would think you would basically want that to occur at a fixed pedal position. Typically I would think this would be calibrated to be near zero pedal, but it might be interesting to have it occur at part throttle at higher engine speeds so that engine braking could be modulated.

Daniel

Engine braking is pretty important in a race car and next time I get a chance, I will be testing negative values to see if I get more engine braking

Quote:

---

Originally Posted by TurboWood

Are you sure about this? I'm still new to this, but engine vs. wheel tq will be gear dependent. If we ignore the trans/rear-end multiplication of TQ then really all we are talking about is the efficiency of these which doesn't seam important to me. In such a case I don't see how you would arrive at negative TQ. It seems more likely to me that these values are just engine.

If I'm right, then a more negative value will result in more engine braking. Negative TQ should just be the FMEP and PMEP of the engine (again, if my understanding is correct). The only parameter we can impact is PMEP by closing the throttle. The zero-fueling TQ will become more negative as engine speed increases due to FMEP. It would be interesting to know if anyone has figured out what this is because I would think you would basically want that to occur at a fixed pedal position. Typically I would think this would be calibrated to be near zero pedal, but it might be interesting to have it occur at part throttle at higher engine speeds so that engine braking could be modulated.

Daniel

---

yes it is gear dependent but the ecu is only tracking this as a 3d field not a 4d field. it also tracks it best in terms of 1:1 transmission ratios.

What is your best guess on what would be the ideal torque table for good engine braking? Highest minus numbers across top row then tapering down (up?) towards the 20% throttle opening row?

From my observation, you can divide the whole map into four parts like cartesian plane with x and y reference axis. Take 70 on rpm axis as Y-axis and 32 on throttle pedal position as X-axis.

You will get four regions on whole map:

A: Rpm < 70 and throttle <32: Could be considered as firing up and acceleration to mid load. Although some values of torque is negative, it's because the rev is quite higher than idle and couldn't be achieved at engine startup. Therefore it must be result of deacceleration, driver reducing throttle opening, which means it's slowing down, no torque supplement required. The engine rotates due it's momentum.
B: Rpm>70 and throttle >32: You rarely encounter very high throttle opening, and very low rev. It must be driver closing throttle at very high throttle opening. So inorder to assist braking torque is negative here, except for near 32 % throttle and high rev.
C: Rpm<70 and throttle >32: This must be due to driver trying hard to gain acceleration at low rev, so torque figure are quite high and postive to assit acceleration.
D: Rpm >70 and throttle >32: This the peak end application that's why torque is again positive.
It should be noted that before 70 rpm torques are generally increasing and after that it's decreasing. It's because you don't need high torque at higher rev, since you are moving, rolling resistance now are less, compared to low rev. It's one of saving fuel and provide more rpm.
More revs could increase the exhuast flow rate, helping turbocharger to spool quicker.
It is used by redbull racing in formula 1.

"Torque maps were a hot topic in July and August 2012 when the FIA issue a directive and made some changes to the way teams were using them during the mid-season. But they are the single most important map for the engineers to use for reference when trying to make sure that the engine is optimized for a given circuit. A directive from the FIA around the time of the German and Hungarian Grands Prix closed a loophole exploited by Red Bull Racing and its engine partner Renault, to improve gas pressure from the exhaust by lowering the torque curve."

why so complicated?!

in this example the map is Engine Power in kW, x axis is pedal percent, y axis is vehicle speed, cause it is an AT car. only on ATs you have the upper line straight values.
on MT cars the upper lines are increasing, as the y axis is engine RPM.

From these maps the ECM will calculate a Desired engine Torque(MT) or desired axle Torque (AT) taking the equation with P=2*pi*M*n on AT n will be calculated from NV ratio, vehicle speed and gear/axle ratio.

when you have the map in this form eg 215kw = 292Hp... that is what the car is rated from the manufacturer, or at least close.
with this map EVERYTHING in the desired Torque calculation starts.
so i highly recommend not to set it too high or you will mess up the whole torque caclulation of the ECU! unfortunately this is what 99% of people do.
you should set it to the engine power you want to achive and also in a range what the engine is capable of achieving.
leave the lower pedal values alone, I normally never touch more than the upper 3 or 4 lines.
of course you can tune throttle response with that table, but be carefull touching the very low values, as it can make the car uncontrollable.
when this Map is to low, the ecu will most certainly claose throttle to achive target power /torque goal.

on newer ECM mostly this map is desired axle torque(always vs RPM), and than it is calculated backwards to engine desired torque, these are a little more tricky to handle but the same rules apply. i Usually chage them by percentage (only upper lines)

on some AT cars there is a little specialilty: 100% pedal line is only reached in kickdown, so it is useful to set upper 2 lines the same