# E46 M3 Sport mode



## Ron Stygar (Mar 31, 2002)

Idle: no change
WOT: no change
Isn't the throttle time from idle to WOT quicker though?
So when doing some side to sides with equal cars, won't the one in sport mode get the initial jump?


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## SteveMedina (Apr 4, 2003)

Hey Ron..how ya doin...

all things being equal, perfect world..and lets say just for testing purposes....the race is 20 feet....

rate that the gas pedal is depressed is equal in both cars.

both drivers apply same rate of pressure to the pedal at the same rate

then yes, sport mode will get the jump.....

right? 

never really thought of it..


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## Pinecone (Apr 3, 2002)

On the other hand, with the drive by wire, there is a maximum rate of adding throttle opening. So even though the system asks for more quicker, doesn't mean you will actually get it.

But within those bounds, the sport mode would tip in the throttle quicker.


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## SteveT (Dec 22, 2001)

There must be an algorithm in the CPU that converts pedal position and rate of change to throttle position and RoC. The dynamics of this are adjusted for the car, maximum opening rates, etc. The coefficients of this algorithm are adjusted when you select sport mode to make the car "feel" more responsive.


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## Ron Stygar (Mar 31, 2002)

Thanks guys.
Just trying to sort out sport mode in my '01 Z3 M coupe, which is currently up on stands with some checking out things on the drivers side floor.

Not too scientific.
Sport mode not:
When I reach in and depress the gas pedal some (jab), with my hand, there is a noticeable delay before anything happens. Once things happen the RPM goes up to 1500>2000. 
Sport mode:
Repeating the above, there is no delay and the RPM goes up to 3000>3500.


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## Pinecone (Apr 3, 2002)

SteveT said:


> *There must be an algorithm in the CPU that converts pedal position and rate of change to throttle position and RoC. The dynamics of this are adjusted for the car, maximum opening rates, etc. The coefficients of this algorithm are adjusted when you select sport mode to make the car "feel" more responsive. *


I am not sure that sport mode allows a higher RoC than normal mode, or just mapping a larger throttole opening for a given position.

If you feed in a digital signal to the system to go from idle throttle position to wide open (virtualy instant pedal to the floor), does sport mode get to wide open earlier?

In other words are the throttle plates actually opening faster, or do they just appear to since the pedal is commanding more opening for less movement.


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## SteveT (Dec 22, 2001)

Pinecone said:


> *I am not sure that sport mode allows a higher RoC than normal mode, or just mapping a larger throttole opening for a given position.
> 
> If you feed in a digital signal to the system to go from idle throttle position to wide open (virtualy instant pedal to the floor), does sport mode get to wide open earlier?
> 
> In other words are the throttle plates actually opening faster, or do they just appear to since the pedal is commanding more opening for less movement. *


Could be there are nonlinearlities in the transfer from pedal to throttle. Normal mode would tend to open the throttle less at the start of pedal motion approaching one to one a WOT, while sport mode could be closer to one to one (linear) throughout. All of this just a guess though.


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## Pinecone (Apr 3, 2002)

SteveT said:


> *Could be there are nonlinearlities in the transfer from pedal to throttle. Normal mode would tend to open the throttle less at the start of pedal motion approaching one to one a WOT, while sport mode could be closer to one to one (linear) throughout. All of this just a guess though. *


From what I have seen, normal is actually 1 to 1. 1/4 pedal is 1/4 throttle, 1/2 = 1/2, etc.

In sport the motion is non-linear, but WOT is still WOT.

Since one way to make an engine quit while running is to open large throttle plates too quickly. The air column cannot acclerate fast enough.

So I woud expect that the DBW system knows what the maximum rate of throttle opening is for any condition (RPM, load, etc) and will allow no more than that, no matter how hard and fast you mash the pedal. Jet engines are like this, no matter how fast you jam the throttle forward, the engine cannot spool up any faster.

But at least with an S54 it doesn't take long to rev, unlike many jet engines.


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## SteveT (Dec 22, 2001)

Pinecone said:


> *From what I have seen, normal is actually 1 to 1. 1/4 pedal is 1/4 throttle, 1/2 = 1/2, etc.
> 
> In sport the motion is non-linear, but WOT is still WOT.
> 
> ...


It makes sense that they would map throttle opening to engine speed.


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## karlblomquist (Apr 4, 2002)

Check out

http://e46m3performance.com/tech/throttle/sport-mode.htm

for some interesting analysis of S54 Sport mode.

-- Karl


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## BB330i (Dec 22, 2001)

*My 2 Cents*

If I were part of the sport button development team I would have taken a simple approach. My gut / butt tells me the curves of the graph above are correct. It is really no different than cable operated throttles with the cable wrapped around a decreasing radius pulley. The difference being the sport button allows you to select between two different curves. As far as fuel / air mix, the throttle position sensor takes care of that as normal.
Too simple?
:dunno:


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