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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Exhaust flap



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      05-11-2012, 12:51 PM   #1
Mike335is
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Exhaust flap

Does driving with exhaust flap open at all time effect the performance of the car in any way weather its stock or tuned??
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      05-11-2012, 02:02 PM   #2
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What does your gut feeling tell you?
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      05-11-2012, 02:18 PM   #3
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Light Seven candles
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      05-11-2012, 02:31 PM   #4
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Quote:
Originally Posted by Sleeper
What does your gut feeling tell you?
I dint think it should but i read somehwhere that if u do that u loose back pressure on take offs, so i wanted to
Make sure and what people think
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      05-11-2012, 02:39 PM   #5
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It's so far downstream that it won't affect much, if anything at all. Full catback exhausts with larger piping and no restrictions make minimal if any gains, so opening up the flap on your exhaust won't really change the end result.
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      05-11-2012, 02:45 PM   #6
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Won't hurt anything and honestly imho it doesn't even sound louder. About the same really, but I drove Subaru's with exhaust's for 10 years so this car is like a Prius (in terms of noise) to me.
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      05-11-2012, 04:08 PM   #7
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Aftermarket exhausts don't have them...
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      05-11-2012, 04:32 PM   #8
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Others my disagree, but when I disconnected the connector behind the brake light to keep the exhaust flap open, I felt like I lost some low end power. I ran this for about a month to see if the ecu would adjust, then decided to reconnect, and power was back within the day.
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      05-11-2012, 05:35 PM   #9
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Quote:
Originally Posted by napboy View Post
Others my disagree, but when I disconnected the connector behind the brake light to keep the exhaust flap open, I felt like I lost some low end power. I ran this for about a month to see if the ecu would adjust, then decided to reconnect, and power was back within the day.
Yeah me too. I hooked it back up and found I liked the low end pull better. Not to mention the louder exhaust note is at most only marginally better after warm up but to its credit it does sound great on cold morning start ups in a garage!

The BMW PE somehow must solve this low end problem, now if I could only figure out how to justify replacing a 2 yr old OEM exhaust system.

Last edited by shortseller; 05-11-2012 at 06:48 PM.
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      05-11-2012, 07:19 PM   #10
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It really wont hurt or gain anything. The flap opens anyways when you get on it above 3000 rpm.
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      05-11-2012, 11:57 PM   #11
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Idk but when I have mine unplugged it seems to run smoother at lower rpms.. When it's plugged it's all jumpy for some reason.
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      05-12-2012, 01:51 AM   #12
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I ran mine open all the time and my 335i has zero issues. Plus it sounds better.
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      05-12-2012, 10:12 AM   #13
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A $1200 BMW performance exhaust by BMW's own numbers only contributes 5hp & 8ftlbs of torque. Its really doubtful you could feel the PE non PE difference seat of the pants let alone a flap at the far end of the exhaust system.

BTW mine has been open for 7K miles with no issues.
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      05-12-2012, 10:18 AM   #14
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I have PE....it has a little nipple you plug the vaccum line for the flap into...therefore, no flap on the PE...and it runs just find and dandy. My only regret is that I didnt do the PE the day I got the car........Ive loved it the 2 years I have had it
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      05-12-2012, 10:39 AM   #15
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Quote:
Originally Posted by Dackz View Post
I have PE....it has a little nipple you plug the vaccum line for the flap into...therefore, no flap on the PE...and it runs just find and dandy. My only regret is that I didnt do the PE the day I got the car........Ive loved it the 2 years I have had it
This is pure speculation...but I wonder if plugging up the vacuum line(at the muffler) vs disconnecting the connector behind the taillight might have a different effects on the ECU? As one method plugs the line closed, the other leavers it perpetually open. This might be why you get a nipple plug with the PE, to close off the vacuum line.

Yeah, the sound of the PE is amazing!
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      05-12-2012, 01:38 PM   #16
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I believe disconnecting the actator throws a shadow code
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      05-12-2012, 01:45 PM   #17
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Disconnecting the actuator gives you 15rwhp lol

In all seriousness, the exhaust flap does nothing but change loudness.
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      05-12-2012, 09:45 PM   #18
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I'm amazed that people say unplugging the solenoid makes no difference in sound. They must be wearing their iPod buds while driving!
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      05-12-2012, 10:33 PM   #19
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Chaps the flap is closed when the engine is cold, once warm the flap is open. The golf tee mod (and all the variations simply opens the flap all the time
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      05-14-2012, 09:24 AM   #20
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Quote:
Originally Posted by napboy View Post
Others my disagree, but when I disconnected the connector behind the brake light to keep the exhaust flap open, I felt like I lost some low end power. I ran this for about a month to see if the ecu would adjust, then decided to reconnect, and power was back within the day.

Where exactly i need to disconnect left or right ?, to make the flap open all the time?
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      05-14-2012, 09:35 AM   #21
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OP... Did you do the golf tee mod or did you disconnect the actuator? I did the golf tee mod and have felt no difference. But EyeGuy might be onto something by saying that disconnecting the actuatuor triggers a shadow code. If by some reason the ECU reads whether the flap is open or closed disconnecting the acutator inhibits the ECU's ablity to read whether it is opend or closed. So it may have some effect (not sure why it would care though). If you opened the flap by disconnecting the actuator plug it back in and drive around. Then do the golf tee mod and see if you feel a difference. Just my $.02.
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