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      01-16-2014, 02:22 PM   #67
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Quote:
Originally Posted by Simon H View Post
I wonder if the USA have different ECU settings etc, to open and close the valves, because mine are definitely open all the time, after warm up.
Mine is open as well all the time (efficient, sport and sport+).
Probably the ECU maps for the US are different.
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      03-12-2014, 08:18 PM   #68
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Quote:
Originally Posted by clubcsl View Post
Mine is open as well all the time (efficient, sport and sport+).
Probably the ECU maps for the US are different.
Let me confirm here
I am 100% if you have the Throttle Resonse at Max super sports the sound is a lot better and I believe this controls the valve!!
So you do have control
I can't be wrong about this as I found the car to be a lot more fun this way!!
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      03-13-2014, 11:42 AM   #69
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Quote:
Originally Posted by soooma View Post
Let me confirm here
I am 100% if you have the Throttle Resonse at Max super sports the sound is a lot better and I believe this controls the valve!!
So you do have control
I can't be wrong about this as I found the car to be a lot more fun this way!!
As I wrote, in mine no matter the engine mode the valves are open all the time.
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      07-22-2014, 02:34 PM   #70
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Quote:
Originally Posted by jmh View Post
Btw you can also modify the vacuum setup so the exhaust valves are ALWAYS open , no need to use chicken/barb wire at all. Looks OEM and works perfectly. Over night the valves will close (loosing vacuum) but as soon as you start the engine they'll be open again.
I will take some detailed pictures/info when I get back from my trip next weekend.


Any updates / news !!!
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      08-30-2014, 05:26 PM   #71
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Another option successful on my 2014 m5. Clamp the hoses when the flaps are open. They will not go back to closed

IV hose line clamp or potato chip back clamp.

***UPDATE***
The Plastic potato chip bag clamps I used leaked by over night so now the opposite happens... They don't open until clamps are off. Would be better putting a short piece of clogged hose in between. Of course added as flaps are vacumed wide open.

Chris

Last edited by hyperguy; 09-06-2014 at 08:10 PM.. Reason: Update
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      08-31-2014, 02:50 AM   #72
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All I can say is "i cut the wire holding the Valves open two weeks ago" put the STD exhaust tips back on to PX the M5, now the inner exhaust pipes are sooted up and the outer one's CLEAN.
So here in the uk they are shut a lot and I always drive Sport+ engine setting.

I am going to wire them Open on my M6 GC CP when it arrives.
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      08-28-2016, 06:07 AM   #73
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Theory states that this is not just a sound reduction exercise by BMW. It is a simple fact that reducing the overall pipe diameter at lower revs increases low end torque.

This theory ties in with the behaviour of the valves (on my F10 M5 at least). With no 'mod', they are closed at cold start up, then open after 90 seconds or so. From then on, at idle, the valves should always be open. There is no need for torque at tickover and the car sounds better with them open.
They then close as you move off and drive at low/med revs, and then open again under WOT or high rev conditions.

You can use zip ties to keep them open. Much easier than wiring, and they won't wear through/corrode like wire. The melting point of nylon is almost twice that of the max temp of the exhaust tips, so they won't melt. I've had mine on for many a lap of the Nordschliefe and they still look brand new. (approx 270 degrees C for nylon vs 150 degrees C for your exhaust tips).

If anyone is near a dyno, and can be bothered to check the low/mid range torque with valves open and closed, then we can put this to bed once and for all. I don't think I can tell, but it's hard to be 100% certain. We need some numbers
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      05-21-2017, 03:04 PM   #74
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I've been running the Akra exhaust system on my F06 M6 for about a year now and recently I am hearing the left exhaust valve rattling in the back...

Is this normal? I think it's because the valve flap became loose, so I might try the ziptie option and hopefully it'll resolve the rattling noise... but just want to know if anyone else' have this rattling noise with their valve flap?

Thanks
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      05-22-2017, 08:28 PM   #75
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The rattle is coming from the connecting arm between the actuator and the valve. I have same issue on my 2016 M5 with M sport exhaust. I found the link below. This is exactly what is happening with my exhaust...and probably yours. You can touch the arm (wear a glove so you don't accidentally burn your hand) and stop the rattling noise. I'm working with Akrapovic now trying to get them to address issue via my local BMW service center (Classic BMW Plano, TX).

http://f10.m5post.com/forums/showthread.php?t=1285252
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      05-23-2017, 02:19 AM   #76
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      12-15-2017, 01:57 PM   #77
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Is there any reason to use uncoated wire versus coated wire?
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