M button and ECU dynamic response vs. WOT only

[Rajmun340]

This is the best time of the year in the South-East when the air is cool but not close yet from frigid/icy temperatures the S65 packs a whole lot more of punch than in the summer months (for people with non FI modified stock engine).

Here is one combo that never ceases to amaze me : with all settings in normal mode accelerate moderately strongly (but not WOT) and then.. press the M button (set to activates Power Sport Plus mode). WOW !! It's *NOT* the same reaction of the engine than going all WOT in standard mode without switching electronically in mid acceleration. I know in theory it's supposed to be equivalent (it changes the throttle mapping) , but i think this does not account for the ECU brutal dynamic reaction as you switch mode *ELECTRONICALLY* 'on the fly' when you are already in some kind of moderate acceleration. I certainly can not get the same acceleration result if i don't use the M button in the middle of an acceleration.

I can't imagine what a SC would feel like, but i don't need one, car feels like it has some freak power and it's all stock (2013 ZCP, picked up in Munich i am the only owner).

PS : One thought crossed my mind, maybe it could be that going all WOT before any prior acceleration the DSC limits the power more intrusively than pressing the M button in mid-acceleration where traction is well established so that the DSC does not interfere. I'd have to try in MDM or DSC off to confirm.

[Rajmun340]

I guess all the car nerds moved on . Back in 2007-13 a thread like this would have fueled a good technical discussion.

[8600RPM]

Hitting m button simply opens tgrottle fully at less pedal depression so you are going from part throttle to full throttle by hitting m button mid throttle when you go from normal to sport

[Rajmun340]

Originally Posted by 8600RPM

Hitting m button simply opens tgrottle fully at less pedal depression so you are going from part throttle to full throttle by hitting m button mid throttle when you go from normal to sport

yes, i know, but last i looked my foot is not capable of moving from half to full throttle in 0.1 micro second more like 300 MILLIsec at best. Point is, ECU get it's curve models instantaneously swapped by software with the M button. computational discontinuities result in a different engine response.
At least in practice i feel a big difference.

[kenwelch]

Here is a link to the "4th Generation M3 Introduction" technical manual.
You will need to login to view the manual.
The MDrive details begin on page 18.

http://www.m3forum.net/m3forum/showthread.php?t=204933

Enjoy

[redpriest]

I should try that sometime, but I pretty much always have the power button on.

[kenwelch]

Originally Posted by redpriest

I should try that sometime, but I pretty much always have the power button on.

From the technical manual:
"The options determine how spontaneously the engine responds to actuation of the accelerator pedal. The maximum engine power is not changed.

Using the power button in the center console, the driver can only choose between "Normal" and "Sport".

"Sport Plus" is only available in the MDrive menu."

[redpriest]

Originally Posted by kenwelch

From the technical manual:
"The options determine how spontaneously the engine responds to actuation of the accelerator pedal. The maximum engine power is not changed.

Using the power button in the center console, the driver can only choose between "Normal" and "Sport".

"Sport Plus" is only available in the MDrive menu."

I never press the power button directly; it's always direct through the M button on the steering wheel, and it's always in Sport Plus. The M Button is one of the very first things I do after I've started the car, haha.

[Rajmun340]

Originally Posted by kenwelch

Here is a link to the "4th Generation M3 Introduction" technical manual.
You will need to login to view the manual.
The MDrive details begin on page 18.

http://www.m3forum.net/m3forum/showthread.php?t=204933

Enjoy

Thank You...hmmm. .. there is really no easy way to say this but..... How about some documentation of our engine ECU 'Torque management' ? Have you looked at or read that ? i guess not... Maybe you could enjoy that See below the table of content.

You guys are answering a highly technical question with marketing prospectus level answers (which i have those too, off course).

1 Overview of torque Manager 5
2 Basis of calculation sizes 8
3 torque calculation 8
4 Calculation lambda efficiencies 12
5 torque interface (CAN) 13
6 Interface for climate control and KSG 13
7 Interface to the ASC / DSC - request torque intervention 14
8 interface for ASC / DSC - feedback torque intervention 15
9 friction 16
10 drag torque 17
11 Maximum indicated torque 19
12 calculating desired torque 20
13 torque filter 21
14 dynamic filter at Wunschmomentgradienten 22
15 Bonanza filter 25
16 Dashpotfilter 25
17 engaging idle controller 26
18 torque limitations 26
19 torque limiter 27
20 Speed ​​Limit 28
21 torques at katschädigenden dropouts 29
22 torques at collapse of Krafstoffdrucks 29
23 torque limit for noise reduction 29
24 torque reserve 30
25 torque reserve for Katheizfunktion 30
26 torque reserve (not implemented in EVT!) With strong steering inputs 32
27 limiting the torque reserve 32
28 torque intervention filling path 33
29 efficiency correction 34
30 Calculation of wi 34
31 Calculation of control edges 35
32 torque intervention ignition path 35
33 Calculation ignition angle 36
14.1.Berechnung Optimal ignition 36
14.2.Berechnung Zündwinkelwirkungsgrade 37
14.2.1. minimum ignition angle 38
14.2.2.Basis ignition angle 38
14.2.3. Calculation ignition angle before engaging 38
14.2.4. Calculation ignition angle after intervention 38
14.2.5. Calculation Eingriffszündwinkel 39
14.3.Berechnung Normalized Zündhaken 41
34 monitoring torque calculation 43
35 hedge torque calculation 43
36 monitoring target torque to actual torque 43
37 monitoring target / actual torque over the entire operating range 44
38 monitoring target / actual torque at PWG Default = 0 44
39 Teilfeuerung with open clamping throttle 45
40 Administered data of torque manager 46
41 variables of torque manager 49

[kenwelch]

Could you share the documentation on ECU torque mgt. Or a link to the document?

[Rajmun340]

Originally Posted by kenwelch

Could you share the documentation on ECU torque mgt. Or a link to the document?

It is all in German
google translated the table of content

I may share if people try the comparison experiment i described and report their result objectively, no answers without trying it specifically on their car.

[crypticc]

I've often thought this but reconcile it to being difference between depressing the accelerator increasing the requested demand from x to z via y vs the power button which instantly shifts the requested torque to z without going via y. The maximum is the same but isn't another factor is the 'rate' of increased demand as well as absolute throttle position that determines how wide to open those throttle bodies?

[asbjorjo]

Originally Posted by JoeM3SSII

yes, i know, but last i looked my foot is not capable of moving from half to full throttle in 0.1 micro second more like 300 MILLIsec at best. Point is, ECU get it's curve models instantaneously swapped by software with the M button. computational discontinuities result in a different engine response.
At least in practice i feel a big difference.

Your foot doesn't have to move. The car has throttle by wire (the position of the pedal is read by a sensor and interpreted by the engine management software), and the various "power" settings simply modifies the response of the throttle pedal from a linear response (normal) to more progressive responses for sport and sport+.

[FType22]

Originally Posted by JoeM3SSII

This is the best time of the year in the South-East when the air is cool but not close yet from frigid/icy temperatures the S65 packs a whole lot more of punch than in the summer months (for people with non FI modified stock engine).

Here is one combo that never ceases to amaze me : with all settings in normal mode accelerate moderately strongly (but not WOT) and then.. press the M button (set to activates Power Sport Plus mode). WOW !! It's *NOT* the same reaction of the engine than going all WOT in standard mode without switching electronically in mid acceleration. I know in theory it's supposed to be equivalent (it changes the throttle mapping) , but i think this does not account for the ECU brutal dynamic reaction as you switch mode *ELECTRONICALLY* 'on the fly' when you are already in some kind of moderate acceleration. I certainly can not get the same acceleration result if i don't use the M button in the middle of an acceleration.

I can't imagine what a SC would feel like, but i don't need one, car feels like it has some freak power and it's all stock (2013 ZCP, picked up in Munich i am the only owner).

PS : One thought crossed my mind, maybe it could be that going all WOT before any prior acceleration the DSC limits the power more intrusively than pressing the M button in mid-acceleration where traction is well established so that the DSC does not interfere. I'd have to try in MDM or DSC off to confirm.

Well I know what I'm going to test today

[Rajmun340]

Originally Posted by crypticc

I've often thought this but reconcile it to being difference between depressing the accelerator increasing the requested demand from x to z via y vs the power button which instantly shifts the requested torque to z without going via y. The maximum is the same but isn't another factor is the 'rate' of increased demand as well as absolute throttle position that determines how wide to open those throttle bodies?

Yes, and the ECU is more than capable of sampling the throttle position every 10-20 ms, so it's not just one intermediary points, even if you trample the throttle in 0.2 sec it will still get 10-20 intermediary points out of it which means plenty of engine cycles in between. Whereas with the button it's instantaneous. Applying instantaneous throttle change (which is what it effectively does) can in fact cause the engine to react differently to timing advance, and it has no time to change VANOS angles, therefore my point ...

...the ECU will put the engine in a different set of parameters than doing it with the foot and from what i can see it's a better way to get the engine going hard.

[Rajmun340]

Originally Posted by asbjorjo

Your foot doesn't have to move. The car has throttle by wire (the position of the pedal is read by a sensor and interpreted by the engine management software), and the various "power" settings simply modifies the response of the throttle pedal from a linear response (normal) to more progressive responses for sport and sport+.

you failed to understand the whole point

[8600RPM]

Tried this and as expected it feels no different than stomping on the throttle

[mjposner]

I used to run full M on but even in normal driving my mpg dropped to 12-14. Now I leave the car in sport by default (no affect on mpg, 17.5) then hit M when I need to feel more power (illusion I know, but the change in the dtc is real)

[New2Roundel]

I never gave much thought of power or sport buttons on most NA cars until I got the M3. There's definitely a noticeable different in the responsiveness and feel of the car. Personally, I keep the car in standard mode until the oil warms up and then press the sport button. My seat of the pants interpretation is that the power button moves the torque curve back a little so that there's more mid range torque than the standard setting. The car definitely feels more beefy in at say, 3500 rpms than it does in the default mode. Having said that, the throttle is also more sensitive to input, so if I'm driving someone else in the car who is not a car person, I leave all the settings in default mode. It's a much smoother experience for the average person.

Having said that, I'd love to see a dyno that compares default and power mode to see if the power and/or torque are shifted to the left a bit. I'm sure someone has done this at some point, given how old our cars are.

[8600RPM]

Originally Posted by New2Roundel

I never gave much thought of power or sport buttons on most NA cars until I got the M3. There's definitely a noticeable different in the responsiveness and feel of the car. Personally, I keep the car in standard mode until the oil warms up and then press the sport button. My seat of the pants interpretation is that the power button moves the torque curve back a little so that there's more mid range torque than the standard setting. The car definitely feels more beefy in at say, 3500 rpms than it does in the default mode. Having said that, the throttle is also more sensitive to input, so if I'm driving someone else in the car who is not a car person, I leave all the settings in default mode. It's a much smoother experience for the average person.

Having said that, I'd love to see a dyno that compares default and power mode to see if the power and/or torque are shifted to the left a bit. I'm sure someone has done this at some point, given how old our cars are.

It does nothing except make,throttle response more sensitive where movement of throttle leads to more signal with less depression of the pedal

[Rajmun340]

Originally Posted by 8600RPM

It does nothing except make,throttle response more sensitive where movement of throttle leads to more signal with less depression of the pedal

That is a short sighted marketing simplistic view that does not account for the fact that the ECU is a time sampled system running on a crystal clock that continuously evaluates all sensors in a closed loop system and picks and modify targets continuously dozen multiple folds per seconds. It's also not a purely linear system. Changing the transfer curve of the throttle response by pressing the M button is like an instantaneous input offset to the system that WILL cause different ECU response than trying to do the same without the M button with your foot.

The system does not stop at the throttle response. That is a common but short sighted view.

[8600RPM]

Actually it's exactly what it does. You are not properly informed . Ask any tuner on here who has seen all the maps. It's a simple throttle adjustment