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      06-22-2012, 02:28 AM   #1
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At what RPM does second exhaust open?

...the second exhaust (inner of the two I assume) open on the 328i? And if one were outside the car, would the sound of the flap opening be audible?
At idle, is only one exhaust open or both? Or is it all dependent on exhaust gas regeneration and emission stuff?
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      06-29-2012, 02:30 PM   #2
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On cold start, the valve is open (both exhausts flowing) for a while until the car begins to warm up and then the valve closes. I'm trying to think back to before I disconnected the valve (25,000 miles ago, mine is always open and I love it) and I don't remember if there's a specific RPM, I think it just opens when you floor it or go past a certain throttle position.

You can't really hear the valve opening, it does make a sound but the exhaust noise itself is much louder. You can hear the exhaust growl more when it opens if you listen with the windows down, though.
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      06-29-2012, 04:37 PM   #3
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Quote:
Originally Posted by Remonster
On cold start, the valve is open (both exhausts flowing) for a while until the car begins to warm up and then the valve closes. I'm trying to think back to before I disconnected the valve (25,000 miles ago, mine is always open and I love it) and I don't remember if there's a specific RPM, I think it just opens when you floor it or go past a certain throttle position.

You can't really hear the valve opening, it does make a sound but the exhaust noise itself is much louder. You can hear the exhaust growl more when it opens if you listen with the windows down, though.
I've noticed this cold start thing! Sounds awesome with both open then it gets warm and I can hear the valve open/close loud and clear OUTSIDE the car (not inside) and it all quietens down nicely.
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      07-02-2012, 08:14 AM   #4
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Like Remonster said its open for about 30 seconds on a cold start then shuts. I took the clip out and fixed mine in the open position this weekend. It didn't make a big difference, but you can tell it's open at lower rpms now. Its now a little louder than it was, but still super quiet IMO. I would say 3000rpm is a good guess as to when it opens, as it used to be silent below that, and I can now hear the car a little bit.
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      07-02-2012, 04:12 PM   #5
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Quote:
Originally Posted by smohr33
Like Remonster said its open for about 30 seconds on a cold start then shuts. I took the clip out and fixed mine in the open position this weekend. It didn't make a big difference, but you can tell it's open at lower rpms now. Its now a little louder than it was, but still super quiet IMO. I would say 3000rpm is a good guess as to when it opens, as it used to be silent below that, and I can now hear the car a little bit.
How does one go about doing this to keep the flap open? Can be enabled again easily?
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      07-02-2012, 04:16 PM   #6
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Yes. There is a metal clip that connects the flap to the motor that opens and closes it. All you have to do is take that clip out, and wire the flap so it is permanently open. Literally a 30 second job. If you don't like it, just push the clip back in, but trust me it doesn't make a huge difference.
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      07-03-2012, 10:51 AM   #7
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Quote:
Originally Posted by smohr33
Yes. There is a metal clip that connects the flap to the motor that opens and closes it. All you have to do is take that clip out, and wire the flap so it is permanently open. Literally a 30 second job. If you don't like it, just push the clip back in, but trust me it doesn't make a huge difference.
Could you posts some pics or a video? I'm not confident!
Although that said, I'm probably not going to bother haha
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      07-03-2012, 01:01 PM   #8
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Stealing this picture from Edmunds Insideline



See the metal clip shaped like a U? Take some needlenose pliers and pull that out. Then just use wire to fix the flap in place, there is a slot where the clip used to sit that works perfect.

It literally takes 30 seconds.
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      07-06-2012, 04:34 PM   #9
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Quote:
Originally Posted by smohr33
Stealing this picture from Edmunds Insideline



See the metal clip shaped like a U? Take some needlenose pliers and pull that out. Then just use wire to fix the flap in place, there is a slot where the clip used to sit that works perfect.

It literally takes 30 seconds.
Ahh yes, looks stupidly simple!
Thanks for that
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      07-09-2012, 11:38 AM   #10
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Does it lower mpg?
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      07-09-2012, 12:58 PM   #11
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Quote:
Originally Posted by kamigawa120
Does it lower mpg?
Good question...
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      07-09-2012, 01:03 PM   #12
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I haven't experiened any difference. I'm not sure how a closed flap in the exhaust would make milage worse, if anything I think it would be better. Either way I think you would be measuring hundreths of a mpg...
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      07-09-2012, 03:52 PM   #13
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Quote:
Originally Posted by smohr33 View Post
I haven't experiened any difference. I'm not sure how a closed flap in the exhaust would make milage worse, if anything I think it would be better. Either way I think you would be measuring hundreths of a mpg...
^^ True, I imagine the difference is negligible.
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      07-09-2012, 09:16 PM   #14
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I removed my clip, and its louder now in comfort mode, due to me always cruising at 50mph ish. Its ludest around 2200rpm and thats where I sit in comfort.

When its in sport, the rpms are at 3000 and its quieter for some reason.

All in all i like, it lets me know theres some power behind this n55

I wish there was a better way to secure the flap though. I used tie wire, and it works, but its a rig up job. Looks very cheap, like it was done on the side of the road, and I dont like that. Im just anal
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      07-09-2012, 09:59 PM   #15
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Quote:
Originally Posted by dd1981 View Post
I wish there was a better way to secure the flap though. I used tie wire, and it works, but its a rig up job. Looks very cheap, like it was done on the side of the road, and I dont like that. Im just anal
But you can't see it though?
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      07-09-2012, 10:15 PM   #16
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Quote:
Originally Posted by Spikey View Post
But you can't see it though?
No, I know you can't, but I know its there. Its fine, untill I upgrade the exhaust.

Im OCD I guess, everything has to be neat.
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      07-09-2012, 10:30 PM   #17
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Quote:
Originally Posted by dd1981 View Post
No, I know you can't, but I know its there. Its fine, untill I upgrade the exhaust.

Im OCD I guess, everything has to be neat.
lol yea, i know how you feel... it's the annoyance factor that you know it's there... it's like invisible scratches ... as the owner you know it's there
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      07-10-2012, 08:31 AM   #18
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Quote:
Originally Posted by dd1981 View Post
No, I know you can't, but I know its there. Its fine, untill I upgrade the exhaust.

Im OCD I guess, everything has to be neat.
I feel the same way, if I owned the car I'd probably put it back the way it was. But since its leased I really don't care
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      07-10-2012, 10:22 AM   #19
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the flap is only to keep the car quiet under low rpm and idle.
Otherwise, you can do without it.
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      07-10-2012, 12:41 PM   #20
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when to do the mod, you wont hear that click sound at the back when turning off the car when it used too :P.

also i feel the car was much more lose when you drive it
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      07-10-2012, 01:32 PM   #21
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Quote:
Originally Posted by Teemo Panda View Post
when to do the mod, you wont hear that click sound at the back when turning off the car when it used too :P.

also i feel the car was much more lose when you drive it
What do you mean loose? Like it performed different? I definetly didn't notice any positive or negative effects.
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      07-12-2012, 11:42 AM   #22
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Quote:
Originally Posted by dd1981 View Post
What do you mean loose? Like it performed different? I definetly didn't notice any positive or negative effects.
Didn't think keeping the exhaust flap open reduced vehicle stability
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