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      10-19-2017, 09:05 PM   #1
SixPost
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650 M Sport owners...

Trying to figure out if my exhaust valves are functional or not.... The way I understand it, secondary exhaust on each side opens up when RPMs are over 3000. On cold start, RPMs hold @ maybe 2500 for 15 seconds or so.... Are your valves open during "cold start"???

Thanks for any input...
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      10-19-2017, 09:17 PM   #2
calbear550
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They are closed for the most part. You can definitely hear them open and the difference when you're either in sport shifting (S1-S7) or in sport or sport + mode. More apparent with spirited driving and faster acceleration. If you want to see what it sounds like without the flap, unplug the black vacuum line that actuates the valve. Regardless of mode or shift setting. It's significantly quieter.
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      10-20-2017, 05:10 PM   #3
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Bump...

Are your valves open on cold start??? If someone can shine a flashlight into the valved muffler outlet and check its status during cold start, it would help me a lot...

Thanks
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      10-20-2017, 06:45 PM   #4
Walt White Coupe
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I haven't looked at them but it sounds like they are open for around 3 or 4 seconds on a cold start.
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      10-30-2017, 03:13 PM   #5
laurenxesq
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can't tell the difference; sport or comfort. I think it's always closed....
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      10-30-2017, 05:23 PM   #6
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I have a Meistershaft system from the cats back. When I start the engine cold the engine holds at an elevated rpm and it is noticeably louder. I have been told that the elevated RPM is mainly to get the engine up to temp quickly for emissions. I have been told that the turbos are bypassed when cold to help warm up the cats.
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      11-04-2017, 02:54 AM   #7
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These cars are definitely louder on cold start for the first 20 seconds or so. However, I've never noticed my valves open any time when the car was parked. I'm almost certain the car has to be in gear and of course over a certain rpm for the valves to open. I can't check mine since now I've got the valves zip tied open.
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      11-04-2017, 05:59 AM   #8
650i2014
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Quote:
Originally Posted by BMWShay View Post
... and of course over a certain rpm for the valves to open.
Not necessarily. In sport mode I notice the valves opening momentarily even when reversing the car; exhaust sounds deeper and you could hear the valves clicking (opening/closing) with the windows down.
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      11-18-2017, 03:06 PM   #9
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for the short time that i had the stock mufflers on, i wired the valves open all the time. its a little louder from the outside but cant really tell the difference inside
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      Today, 07:25 PM   #10
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I presume that my recently purchased (Sep.13/2017) 2006 M6 coupe has completely stock exhaust. It is definitely louder when starting up cold in the morning but soon quiets down. It sure gets quite a bit louder when I depress the "M" (for "Magic") button and then the accelerator. I don't think I have to do anything to my exhaust system. My wife complains that, just like she did about my 2003 Porsche Boxster S, "it's too loud and too fast". Funny, that is just what I like about it. She should have known what she was in for when she married me in 1966. At that time I was driving a factory-tuned 1963 Morgan 4/4 which I had brought back from Europe after serving there with the Canadian Army for three years from 1961 to 1964
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