Exhaust Flap DME Control?

NoQuarter

Major
Nov 24, 2017
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Indiana, USA
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What is the logic when the DME controls the exhaust flap?

Is it RPM based?
How does it change with sport mode, sport+ ?
 

jyamona

Captain
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Nov 7, 2016
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Philly
I think its a PWM signal, it is used to control the second LPFP

Not without a good bit of logic I had to change, as the way the coding was by default it did not lend itself to a straight forward on/off control.

Stock operation has a default position (table: Static Exhaust Flap Position) under a certain MPH (table: Maximum Speed for Static Exhaust Flap). Then above that speed, it is open/closed based on driver torque request (table Z data, axis are gear and rpm). There you'll see the 4 possible tables. Only things that matter are trans (AT/MT) and convertible top (open/closed). Sport mode does not seem to matter on N54.
 

NoQuarter

Major
Nov 24, 2017
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Indiana, USA
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Thanks for the response.

It seems this could be used to control vacuum operated exhaust cutouts but I wouldn't want that all the time. Sport mode I think would have to be a minimum amount of control.

I suppose a manual switch that operates the cutouts is easy enough, but a nice enhancement would be
switch 1, DME controlled cutouts,
switch 2, manual override (open cutouts)

Premium - A canbox that picks up sport mode setting then operates the relay to actuate the vacuum switch

anyone know the sport mode canbus messages?
 

aus335iguy

Colonel
Nov 18, 2017
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335i DCT 2009
Thanks for the response.

It seems this could be used to control vacuum operated exhaust cutouts but I wouldn't want that all the time. Sport mode I think would have to be a minimum amount of control.

I suppose a manual switch that operates the cutouts is easy enough, but a nice enhancement would be
switch 1, DME controlled cutouts,
switch 2, manual override (open cutouts)

Premium - A canbox that picks up sport mode setting then operates the relay to actuate the vacuum switch

anyone know the sport mode canbus messages?
I think we discussed the can bus messages in M3DCT swap thread at some point but the specific messages didn't get a mention. Theres a remote control circuit that you can build with bits from eBay that would do much of what you want except integrate with the CAN BUS although it wouldn't be hard to take it that step further to control it from a can shield