[SatinblkF90]

Hey guys, just had a question regarding exactly how the exhaust button beside gear lever works.

My question is only pertaining to engine in sport plus mode, with exhaust button turned off (no green light) I know it disabled ASD, and closes the exhaust valves, but what happens when you go WOT, in this mode does full acceleration even with button off override the closed setting and turn them on, or are they simply closed all the time no matter how you drive it?

Somebody mentioned in another thread that on the x5m with engine in sport+ mode, even when you shut valves off using the exhaust button, it still opens them when going full throttle, so I'm wondering if the f90 is programmed the same way or not.

[Evil Derboy]

The car still has to open the valves under higher engine loads to protect the system. My understanding on the F90 is the that exhaust button only affects ASD. I read this somewhere but haven’t tested it myself.

[trev230]

It turns the ASD on and off as well as the exaggerated pops and bangs

[pbonsalb]

I unplugged the amplifier in my car. Thinking about adding real sound with downpipes.

[SatinblkF90]

Originally Posted by Moonstone_UK

The car still has to open the valves under higher engine loads to protect the system. My understanding on the F90 is the that exhaust button only affects ASD. I read this somewhere but haven’t tested it myself.

It's not only ASD it closes exhaust valves as well. The question is when off under full throttle do they automatically open valves again in the off setting or stay closed at all times

[smbsocal]

I unplugged the exhaust valve connectors a couple of weeks ago so the valves are always open. The exhaust button definitely has a impact on the pop and bangs as well.

[MSchfiftyFive]

The valves have to open independently of the button based on engine load regardless of the engine setting. At WOT the valves open in any engine mode, and then open at lower engine loads in sport and lower still in sport+, the button adds pops and bangs up to ~45MPH, and sound amplification. It may also open the valves at idle in S+, but they'll open on their own at pretty low throttle load in S+ regardless because there's no pedal deadening (throttle plate and pedal position are 1/1) in that mode and the car needs the valves open to most freely flow the volume of exhaust gases through.

S and RS Audi's operate in about the same way w/ their active valved setups.

[SenorFunkyPants]

[SatinblkF90]

Originally Posted by SenorFunkyPants

Thanks for this. So from this part of the owners manual it has me questioning if under WOT in the OFF setting for exhaust button if the valves do in fact open or not. It sounds like it’s saying based on the button it’s either always open or always closed with no automatic changes based on throttle input.


The other way I understand is it might mean that whenever it does decide to open/close it’s just saying it won’t open or close halfway or 3/4 way but always fully open/close and never in a partial way. If that’s what it means then there is no reason to assume it won’t fully open them at WOT with the off setting.


“ The exhaust flap cannot adopt an intermediate setting; it is either fully opened or closed. The flap
moves towards the respective mechanical end stop using pulse-width modulated signals (PWM
signals). If faults are detected or the actuation stops, or after the engine has been stopped, the
preferred position is the closed position. On vehicles with the M Sport exhaust system, the exhaust
flap is open in Sport mode.”

[SatinblkF90]

One other thing, related to sound I just found out that for engine mode setting sport plus vs sport, that sport does not burble as much as sport+, and also has a bit less throttle sensitivity. In terms of power/boost does anyone know if engine mode sport/sport+ power wise are identical or is there a power difference between them?

[brava09]

Originally Posted by SatinblkF90

One other thing, related to sound I just found out that for engine mode setting sport plus vs sport, that sport does not burble as much as sport+, and also has a bit less throttle sensitivity. In terms of power/boost does anyone know if engine mode sport/sport+ power wise are identical or is there a power difference between them?

No power difference between engine modes

[SatinblkF90]

Originally Posted by brava09

No power difference between engine modes

Good to know. Even efficient mode, or that one must be less?

[brava09]

Originally Posted by SatinblkF90

Good to know. Even efficient mode, or that one must be less?

Same power for efficient mode

[SenorFunkyPants]

Originally Posted by SatinblkF90

Good to know. Even efficient mode, or that one must be less?

IIRC the engine mode setting changes how the DME/ECU uses the output from the throttle pedal position to instruct the fuel injection system.
For example...in efficient mode, full throttle pedal depression will be required to achieve full power....lightly in a fairly linear way.
Where'as in Sport and Sport+ it will be far less linear making the engine more responsive for less throttle pedal depression.
ISTC that in some earlier M models you would reach full power with the throttle pedal depressed ~70% in Sport mode.

[SatinblkF90]

Yes, and in addition to the pedal position it also seems to make the exhaust/ASD progressively louder moving from efficient up to sport+ and continues in this regard I also found with the drivelogic settings 1-3 producing further pedal sensitivity within each engine map setting.

[MSchfiftyFive]

The actuators for these flaps are generic and reused across manufacturers, they have the same 3 inputs, the manual does a great marketing approved intentionally vague explanation, "...at high engine speeds and loads, counter pressure can be reduced by operating the exhaust flap", heh, the PWM line gets the "open me" signal from the DME at WOT in any engine mode because the car doesn't limit power at WOT in any engine mode. The signal via the PWM from the DME overrides any setting from the button, but the flap itself is either open or closed. Interesting to see the M Sport exhaust defaults the flap to open in Sport.

The car always makes the same power at WOT in each engine mode, but the "pedal deadening" algorithm changes in each mode, which is why 25% throttle in Efficient barely moves and 25% in Sport+ is giving all the biscuits. It's effectively "limiting power" by keeping the throttle plate more and more closed relative to pedal position as you step back from Sport+, which is another super common, well mimicked process across the industry now.

[SatinblkF90]

Originally Posted by MSchfiftyFive

The actuators for these flaps are generic and reused across manufacturers, they have the same 3 inputs, the manual does a great marketing approved intentionally vague explanation, "...at high engine speeds and loads, counter pressure can be reduced by operating the exhaust flap", heh, the PWM line gets the "open me" signal from the DME at WOT in any engine mode because the car doesn't limit power at WOT in any engine mode. The signal via the PWM from the DME overrides any setting from the button, but the flap itself is either open or closed. Interesting to see the M Sport exhaust defaults the flap to open in Sport.

The car always makes the same power at WOT in each engine mode, but the "pedal deadening" algorithm changes in each mode, which is why 25% throttle in Efficient barely moves and 25% in Sport+ is giving all the biscuits. It's effectively "limiting power" by keeping the throttle plate more and more closed relative to pedal position as you step back from Sport+, which is another super common, well mimicked process across the industry now.

Can you explain what you mean by this “ The signal via the PWM from the DME overrides any setting from the button, but the flap itself is either open or closed.”

So at WOT the flap is closed but valves are open?


Regarding the pedal sensitivity on the different engine modes, so the way I see it is it’s basically the exact same idea as using a “pedal commander” type product which are widely known to make throttle tricked to make the car think your pushing the gas down more than your actually doing.

Essentially sport vs sport plus at WOT only difference really is that the sport plus will respond slightly quicker from the get go (slight jump from sensitive throttle) but if you measured the 60-130mph time, pushing the gas from 50 (not exactly at 60) for example since power output is identical the times it puts down in both modes, even efficient mode for that matter would all be identical if I’m understanding this right. In addition the sound through exhaust/ASD (speakers) is the second additional change that is being “amplified” when moving from efficient-sport-sport plus. Plus d1-d2-d3 changing how it shifts as well as further increasing pedal response in each engine mode. This is how it feels
To me so far.

[ashmostro]

Originally Posted by SatinblkF90

Can you explain what you mean by this “ The signal via the PWM from the DME overrides any setting from the button, but the flap itself is either open or closed.”

So at WOT the flap is closed but valves are open?

In this context, “flap” and “valves” are the same thing.

It’s already been stated, but the button primarily influences pops and bangs, and ASD, while also adding *some* increased aggressiveness to the engine mode selection’s impact on when the valves open. But in general, what your right foot is doing is what has the most impact on the valves’ position at any point in time.