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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N55 Turbo Engine / Drivetrain / Exhaust Modifications > Exhaust valve question
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      10-01-2012, 02:06 AM   #1
Walt
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Exhaust valve question

I put my exhaust valve back on. I had it completely unbolted before.

It is in the open position when the car is off. When the car starts, it closes right away for about 30 seconds. Once the idle has settled, it opens back up. There are different emissions reasons why perhaps this might be the right way, but it is contrary to what most people have been saying.

There is only one way to put it on (it has to match the valve's clockwise position when the actuator is clockwise). Otherwise it would not be able to turn at all. So it is not bolted on backwards or anything.

At normal idle, in any mode, after 30 seconds, it is always open. I want to make sure the valve isn't somehow electrically backwards, because if it really does open at full throttle, then in my case it would close it.

Can someone please confirm by looking into the exhaust with a flashlight? Is the valve in the open position when the car is off, and closes right away on start-up? The car was not really cold when I was looking at this.

I noticed that even with the exhaust valve wired open like I had it, it would sound noticeably quieter after a bit, so please try not to go off of sound.

Thanks.
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      10-01-2012, 06:39 PM   #2
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I have mine wired open too, but you are right after about 10 seconds it seems like it gets so much quieter...anyone know why?? and how to not make that happen?
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      10-01-2012, 11:17 PM   #3
Walt
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Right now though, I plan to leave it on. Can anyone confirm it is in the open position when the car is off and closes on start up initially?

If it really is open once idle settles in, I wonder when it would go closed again. Maybe under slight load to increase back pressure and therefore low end torque.
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      10-02-2012, 10:49 AM   #4
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bump!! bc now i dont know if I have it wired in the open or closed position!.. I believe its in the open position as I tried both. but still! help!!


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      10-02-2012, 02:58 PM   #5
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Vikz,

If you take a flashlight you can look into the exhaust and see the flapper, about 1/2 way around the bend (on a 335). It should be no problem to tell if it is closed or open.You can also feel the flow, especially if you have someone sit in the car and rev it.
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      10-02-2012, 03:57 PM   #6
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Quote:
Originally Posted by Walt View Post
Vikz,

If you take a flashlight you can look into the exhaust and see the flapper, about 1/2 way around the bend (on a 335). It should be no problem to tell if it is closed or open.You can also feel the flow, especially if you have someone sit in the car and rev it.


thanks...in that case mine is open, and this "mod" makes little to no difference AT ALL as far as sound goes...it sounds great on start up, but like you mentioned about 10 seconds or so later, it quiets down big time..this sucks!! makes me miss my E92 335i!
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      10-04-2012, 08:52 AM   #7
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any ideas why with the valve wired in the "open" position, I still get an awesome sound on start up--then 10 seconds later it gets quiet as sh*t!!???



I miss my E92 with the N54 damn it!
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      10-05-2012, 07:06 AM   #8
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To the OP, mine does the same thing with the Perf. Exhaust.
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      10-13-2012, 03:37 PM   #9
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You need to remove that spring clip and wire the flapper open. Will sound better.
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      10-13-2012, 06:05 PM   #10
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But the performance exhaust sounds loud under acceleration, right?
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      10-14-2012, 12:14 AM   #11
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Quote:
Originally Posted by justinnum1 View Post
But the performance exhaust sounds loud under acceleration, right?

Imo not much louder at all under acceleration when i kept my window open to liste... My brother and my wife both say they can hear me coming down the street now whereas they could not w/ the stock.. Soo
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      10-14-2012, 03:13 PM   #12
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Sounds a lot better than stock all the time. Under some level of acceleration, the stock system will open the flapper on the driver's side exhaust pipe and you'll get an additional exhaust note; but the M-Performance exhaust is louder under acceleration than the stock exhaust (I heard both). With the "golf tee" mod, both exhausts will be louder (and you won't have the mixed clean/dirty exhaust pipes) but the M-Performance is definately louder.
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