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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning bad rattle coming from exhaust.

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      01-03-2019, 06:33 PM   #1
maxrev30
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bad rattle coming from exhaust.

So i finally picked up a 2015 m235i xdrive.

It is in very very good condition and got it for a very good price.

although after having it for 3 days now I've noticed its making a very loud rattle from the left pipe on the exhaust.

It has the m performance exhaust on it and after taking a look under the car i noticed a wire that is just tapped up and there is no electronic piece hooked to the exhaust. Which I'm guessing goes to the electric dump in the car.

I'm wondering if the dump isn't hooked up could this cause the plate inside the exhaust to rattle because it's not getting any power to the dump to hold it in place or could it actually be busted?

thanks for any help/pointers!
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      01-03-2019, 07:38 PM   #2
serrated
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Quote:
Originally Posted by maxrev30 View Post
So i finally picked up a 2015 m235i xdrive.

It is in very very good condition and got it for a very good price.

although after having it for 3 days now I've noticed its making a very loud rattle from the left pipe on the exhaust.

It has the m performance exhaust on it and after taking a look under the car i noticed a wire that is just tapped up and there is no electronic piece hooked to the exhaust. Which I'm guessing goes to the electric dump in the car.

I'm wondering if the dump isn't hooked up could this cause the plate inside the exhaust to rattle because it's not getting any power to the dump to hold it in place or could it actually be busted?

thanks for any help/pointers!
it's probably the exhaust flap/valve. i had the MPE on my m2 and they had a rattle issue that was fixed in a later revision. (they replaced mine completely, and the guy who owns it now had it replaced again, so it's on the third exhaust lol)
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      01-03-2019, 07:41 PM   #3
maxrev30
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Quote:
Originally Posted by serrated View Post
Quote:
Originally Posted by maxrev30 View Post
So i finally picked up a 2015 m235i xdrive.

It is in very very good condition and got it for a very good price.

although after having it for 3 days now I've noticed its making a very loud rattle from the left pipe on the exhaust.

It has the m performance exhaust on it and after taking a look under the car i noticed a wire that is just tapped up and there is no electronic piece hooked to the exhaust. Which I'm guessing goes to the electric dump in the car.

I'm wondering if the dump isn't hooked up could this cause the plate inside the exhaust to rattle because it's not getting any power to the dump to hold it in place or could it actually be busted?

thanks for any help/pointers!
it's probably the exhaust flap/valve. i had the MPE on my m2 and they had a rattle issue that was fixed in a later revision. (they replaced mine completely, and the guy who owns it now had it replaced again, so it's on the third exhaust lol)
Hey thanks a bunch for the reply! I called the dealership to see if the car had a certified pre owned warranty and they told me i needed to have the previous owner change it into my name. when he does that i will bring the car in and have them fix it. ill probably end up building my own exhaust anyways! so have bmw fix it then sell the m sport exhaust.
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      01-04-2019, 07:15 PM   #4
Luftwaffe1O1
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Its happened to me a few times, i have an m2 exhaust ready to go on, i will probably remove/disconnect the flap.
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      01-07-2019, 09:59 AM   #5
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Quote:
Originally Posted by Luftwaffe1O1 View Post
Its happened to me a few times, i have an m2 exhaust ready to go on, i will probably remove/disconnect the flap.
Hey man, It's Iceman00 from Bimmerforums. You still have the Z3 I see....

Do you have any pictures of the M2 exhaust, what makes it different?
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      01-22-2019, 01:51 PM   #6
Samson427
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Hi, I had the same problem on my 2014 228, from my understanding the dealer will tell you to replace the muffler. At least they did for my nonMPE exhaust. I know you can also do a valve delete but I don't know the process for it, if out of warranty it is a much cheaper option.

I had one dealership say it was covered under CPO due to it making a noise, while the other dealer did not believe it should be covered under CPO. I would call around and ask if you want to go the dealer route. I think it is a pretty common problem.

I see you pretty much already came to this conclusion but just wanted to share my experience as well. Good luck!
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      01-22-2019, 01:57 PM   #7
maxrev30
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Quote:
Originally Posted by Samson427 View Post
Hi, I had the same problem on my 2014 228, from my understanding the dealer will tell you to replace the muffler. At least they did for my nonMPE exhaust. I know you can also do a valve delete but I don't know the process for it, if out of warranty it is a much cheaper option.

I had one dealership say it was covered under CPO due to it making a noise, while the other dealer did not believe it should be covered under CPO. I would call around and ask if you want to go the dealer route. I think it is a pretty common problem.

I see you pretty much already came to this conclusion but just wanted to share my experience as well. Good luck!
Quote:
Originally Posted by Samson427 View Post
Hi, I had the same problem on my 2014 228, from my understanding the dealer will tell you to replace the muffler. At least they did for my nonMPE exhaust. I know you can also do a valve delete but I don't know the process for it, if out of warranty it is a much cheaper option.

I had one dealership say it was covered under CPO due to it making a noise, while the other dealer did not believe it should be covered under CPO. I would call around and ask if you want to go the dealer route. I think it is a pretty common problem.

I see you pretty much already came to this conclusion but just wanted to share my experience as well. Good luck!

Yes so i am dealing with the old owner to get the cpo warranty transferred into my named then I'll bring it in and have it looked at. but for the mean time i took a piece of welding rod and wrapped the the valve open which holds it still. fixed the super annoying rattle for now until i have the cpo warranty transferred over to see if bmw will replace the parts.

Also thank you for the insight!
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      01-22-2019, 05:42 PM   #8
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Does your rattle only happen on start-up for about 30-60 seconds or is it constant?
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      01-23-2019, 03:53 PM   #9
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Does the 2016 M235i (F23) exhaust have a valve that give it the dual outlet in Sport and sport + mode?

I cannot find anything in my owners manual.

It is stock as far as I can tell.

Greg
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      01-23-2019, 03:55 PM   #10
maxrev30
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Quote:
Originally Posted by wichitagreg View Post
Does the 2016 M235i (F23) exhaust have a valve that give it the dual outlet in Sport and sport + mode?

I cannot find anything in my owners manual.

It is stock as far as I can tell.

Greg
I'm not sure myself. Mine has the M sport exhaust. and if you look inside the left pip you can see the valve.
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      09-02-2019, 03:04 PM   #11
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Look at this thread...

dreadful exhaust flap rattle .
https://r.tapatalk.com/shareLink?sha...8;share_type=t
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      09-12-2019, 04:23 PM   #12
maxrev30
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Quote:
Originally Posted by maverick83 View Post
Look at this thread...

dreadful exhaust flap rattle .
https://r.tapatalk.com/shareLink?sha...8;share_type=t
Thank you for that link! funny enough what's holding mine from rattling right now is welding wire holding the flap wide open. Temporary issue to hold me over tell i put a full exhaust on it.
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      09-21-2019, 06:00 PM   #13
Praetor353
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Quote:
Originally Posted by wichitagreg View Post
Does the 2016 M235i (F23) exhaust have a valve that give it the dual outlet in Sport and sport + mode?

I cannot find anything in my owners manual.

It is stock as far as I can tell.

Greg
For M235i stock exhaust, that is an anti drone valve. I know other bmw models use this setup too, and not sure if it's identical on the Mperf muffler. It closes in certain situations to prevent excess cabin NVH when the engine speed drops below 1500rpm-ish, I'm guessing because the ZF8 in D constantly wants to be between 1100-1500. Others have reported it being open as well as shut in different modes, as well as open and shut sometimes on startup. Seemed inconclusive, but none of that info really concerns me because the idea of a PCM controlled valve is sacrilege to me. FWIW, there's not much increase in drone with it open in all driving situations. Most noticeable on cold start, for a brief 10-15 seconds

I removed the spring that connects motor to valve, then ended up tack welding the valve in the open position. I tried JB weld a couple times at first, but it vibrated loose each time and made a racket. I welded it in a way where I can break it off later and return to normal function if needed.
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