Driver Demand Torque? Why some tunes aren't changed...

[Mustang]

I've been doing a lot of comparing stock vs the FRPP 2 and FRPP3 tunes, along with a few other ones I've seen people post. I think I've confused myself a bit. Between stock and FRPP2, there are definitely changes in the driver demand TQ settings, but only in the low half of the RPM range, and only in the mid accelerator position settings. It's my understanding that FRPP2 and FRPP3 both have different, but higher power numbers according to Ford's own graphs, however stock/FRPP2/FRPP3 all have exactly the same numbers in most of the chart, including the highest (90% pedal).

I would have thought that one would need to or want to set it at how much torque the engine is actually capable of.

In some other tunes, I found a whipple tune for example, the driver demand table was clearly changed and the numbers "make sense" in that they more or less mirror the gentle 3D slope of the factory tune, but obviously with way higher numbers. I've found other tunes however, where the entire top few rows (Let's call it the last 4 rows) have exactly the same TQ number (top to bottom) e.g. 49.7% = 315 (No matter the RPM) and 57.2% = 350 (No matter the RPM). In these tunes, the torque peak is higher than stock, but I don't think the tunes were for a completely stock car.

I know that the engine can only make the torque it can make, regardless of what the driver demands. So theoretically, could one set the entire table to 900 for example? I guess what I'm getting at is setting it too low would leave torque on the table (bad) but setting it too high wouldn't actually get more power than possible, but also wouldn't leave any on the table? I'm guessing this is for pedal feel more than anything else, but perhaps I have got that confused with the driver demand > pedal characteristics?

Sorry for all the questions - I do try to figure them out using both the "Coyote Cookbook" and the "Master EFI Tuner" books before bothering all of you.
Thank you

[B E N]

Driver demand is just a driver feel thing, WOT doesn't rely on it so it doesn't really matter what it is capped at.

If you set the entire table to 900 its going to try to make max power all the time, regardless of throttle input. Think of it as how much the throttle blade moves in relationship to the accelerator pedal.

[Mustang]

Thank you very much Ben, that makes sense!

[Grim5.0]

the manual frpp tunes dont adjust DD in the tables, its in the tq invers axis that the tables feed into. could you be looking at an auto vs manual tune? auto has very different DD. At WOT DD can limit output, which is why most will bump the last row to keep the TQ ratio on the high side of 1. on a FI tune most ive seen change the TB WOT entry and exit points to a lower value so DD is used less and less. It would then seem necessary to adjust the DD tables so the now larger WOT region would not be a limit if left stock. im assuming on this for FI as my only experience is NA with the ecu.

Murfie- Driver demand is torque at the wheel. Autos and manuals have different driver demand calculations as a manual transmits torque to the wheels different than an auto does. Most of the driver demand in an auto actual is lost to slip in the transmission calculations, so peak torque is demanded until the RPM it occurs at. Actual wheel torque the driver is demanding is then in the transmission settings. Then other calibrations, like the GT350, have maximum engine torque tables that limit the driver demand before the torque is even calculated through the clutch into the transmission. Then if the engine is calibrated incorrectly and the ECU thinks there is more or less air Load than there actually is, the torque comes out wrong. In order to keep the pedal having a feeling of still being in control, ETC torque is corrected to what ever engine brake torque is being calculated as, so if the pedal is decrease, torque will be, if its increased torque will be. People will say changes only make the pedal feel different. Other manual transmission calibrations the DD table will look just like a dyno graph of torque at the wheels for different throttle positions. There are so many different paths in every ECU, its more about following the right torque path and correcting what needs to be corrected.

[Mustang]

Thank you Grim5.0 - All of the tunes I've been looking at are manuals because I do see that the Auto's have a different table setup. The frpp tunes I've looked at have a torque increase "bump" kind of framed between 11.8 to 33.2% pedal and 350-2500 RPM. I'm specifically referring to ECM 1685 (Engine > Torque Management > Driver Demand > PRN1). ECM 1684 (Launch) is substantially changed though framed between 8.9 to 64.9% pedal and the entire rev range.

I know the frpp tunes are much "torquier" in feeling when driving it, and ford supposedly wrung out around 40 ft/lbs more tq around 1500 rpm. But yeah this is for a NA car. Specifically I'm trying to write an e85 tune using the FRPP as the base since I have the physical hardware on the car, and because I know the frpp tables are more aggressive as a starting point for timing and such. Thank you again for the explanation.

[Grim5.0]

i wonder if you have a previously modified tune file. My stock and frpp2 tunes (purchased from frpp direct) have the exact same DD tables for all 7 or 8 of them. the tables themselves are different in the ranges you mentioned but thats within the same tune.

its all in the ignition timing. Stock borderline is neutered for pump 87. I cant recall of any other limits they removed besides allowing timing to hit harder/quicker and with less restraint on those tunes. The octane learn is forced to a -1 to add in from ecm 38052 and the borderline tables are built up so that MBT is hit pretty much around the clock except for a few areas at part throttle and then wot. And then those will still hit MBT with the knock sensors adding. I ran that tune on e85 few months back. Adjust the lambda stoich to 9.85 in ecm 2300 (or get a tester and calculate the stoich of your E), copy the cranking fuel FFV values from 21902 to 1219 and thats it.

you can use the frpp2/3 for flex as all the tables are there, have done that too when switching from 93-e85. you should dial the maf in first though on gas

[B E N]

I did find tweaking the values early in the curve really helped the lack of IMRC and runner length when I went to blower, as a side effect it feels like a beast on the highway. It is really made a fun car to drive, you always have power available. Once you have the tune acting well its definitely worth working on driver demand.

[veeefour]

DD torque has to match your torque model - there's some wiggle room so you can change few high cells in DD while tuning N/A car.
But anything major like mani, cams or boost your DD has to be changed to match your new torque model no matter what some say.

[B E N]

The method I used was ETC throttle angle error, engine RPM in column and APPS in row axis. If this number is positive the DD is too high. But your tune needs to be pretty straight before you start messing with this. I then increased the values early in the curve which seemed to help some of the stumbling I had when cold at low speeds, and it didn't introduce a lot of angle error.

[sportinawoody]

what unit did you use for APPS ? i'm assuming millivolts since it only allows volts or millivolts and my apps shows some radical numbers that doesnt correspond to voltage

[Grim5.0]

it should be % and youd want to match up to what your labels on the DD tables show.