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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning Exhaust only out of one side

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      09-08-2014, 07:53 PM   #1
horsepower_and_hounds
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Exhaust only out of one side

1st I will say is I thought I knew how the exhaust should work but I am 675mi into my break in period and i don't think the l/h side of the exhaust has opened. I have been in comfort mode for the whole time...does it just open in sport? Need to be driven hard? I did a long highway drive Sunday and when I pulled onto my street I stopped and checked the outlets...the left side is completely cold. The right has some soot in the pipe but the left side is completely virgin...
Can someone enlighten me?
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      09-08-2014, 08:02 PM   #2
pikcachu
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i think it only opens when you push it over 4k rpm
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      09-08-2014, 08:37 PM   #3
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Quote:
Originally Posted by pikcachu View Post
i think it only opens when you push it over 4k rpm
Is this true?
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      09-08-2014, 08:51 PM   #4
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The left side valve open rate is heat related and it takes place up front with aux pumps...so go in and have it checked. I know of three in our area, and they all have left side open up in about 35 to 40 seconds. I don't think comfort as anything to do with it...but I could be wrong on that. The electronic action back there on left side is actuated by up front temps in intake.
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      09-08-2014, 09:09 PM   #5
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Quote:
Originally Posted by nzw212 View Post
Is this true?
It is my understanding also that in comfort it only opens above 4k rpm.
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      09-08-2014, 09:39 PM   #6
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Quote:
Originally Posted by zkeeper View Post
The left side valve open rate is heat related and it takes place up front with aux pumps...so go in and have it checked. I know of three in our area, and they all have left side open up in about 35 to 40 seconds. I don't think comfort as anything to do with it...but I could be wrong on that. The electronic action back there on left side is actuated by up front temps in intake.
It opens in sport all the time. Exception to this is it is shut during startup in order to create more resistance to warm the cat up from what I understand. Same reason the car settles into a lower idle. Helps emissions.
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      09-09-2014, 07:49 AM   #7
horsepower_and_hounds
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That is what I want to hear....I will re-evaluate when it is broke in. Right now i only drive in comfort and below 4k per instructions. I try to vary the load the best I can and am not using cruise.
I had noticed after my 1/2hr drive home the l/h exhaust pipe was cold.....and there is absolutly no exhaust residue inside like it is brand new. I am at 690mi so half way. Lookinfg forward to the 1200 milestone
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      09-09-2014, 09:16 AM   #8
Jerich0
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I studied the exhaust valve issue as well here are my results:

Exhaust valve closed when cold startup for 15 - 20 seconds and then opens.

Valve open ALL THE TIME at least on idle on any driving mode. (When engine warmed up)

Temps in my area are around 75-90F
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      09-09-2014, 12:39 PM   #9
horsepower_and_hounds
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Quote:
Originally Posted by Jerich0 View Post
I studied the exhaust valve issue as well here are my results:

Exhaust valve closed when cold startup for 15 - 20 seconds and then opens.

Valve open ALL THE TIME at least on idle on any driving mode. (When engine warmed up)

Temps in my area are around 75-90F
Now that is not what I wanted to hear.........interesting. Maybe I need to choke the chicken to break it loose
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      09-09-2014, 07:48 PM   #10
horsepower_and_hounds
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Ok so today I drove home in sport mode..."very easy" to abide by the break in rules and the exhaust was open when I pulled into the driveway. I looked up the exhaust and it was barely cracked open so I guess it opens and closes based on a bunch of parameters. All i know is that it never opened in comfort mode driven easy. At least I know it works....
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      09-09-2014, 09:31 PM   #11
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Which side closes...passenger?
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      09-10-2014, 03:09 AM   #12
horsepower_and_hounds
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driver....the side with the flapper
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      09-10-2014, 12:31 PM   #13
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To me when its open its quieter... Closed is louder!
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      09-10-2014, 01:40 PM   #14
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It is. Open is the longet quieter side of the mufler closed is the short loud side.
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      09-21-2014, 12:38 AM   #15
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Do you know if the performance exhaust works the same way? Or does this one is open all the time?
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