[studio54]

Hello,

I don't know if it's because i am full catless now but i noticed when i blip the throttle that my exhaust does a sound similar (to my ears) to wastegate rattle.

It's just when you are stationnary, and you blip the throttle, when rpm fall next to idle, let's say from 750rpm to 650rm, very short range like a half second, it does a rattle snake zzzzz sound.

I believed at first and was afraid (new turbos) it could be wastegate rattle again, but i does sound the same with wastegate open, and this sound is shorter than infamous wg rattle. It's probably a normal sound that most exhaust does, and it's probably more audible when you are catless.

I can't find online how it's called? on my car it's very audible in indoor parkings.

I find some sound clip online of 128i to make sure it's not wastegate rattle cause 128i engines don't have turbos :

https://www.youtube.com/watch?v=IX7cpS2nFdo at 10 seconds, at 14 seconds [...] and so on.

It's this exact sound. Anyone what causes this sound and how it's called?

I do not particulary like this sound, what can i do to reduce this? resonators ?

Thanks !!

[relative4]

Google "bmw golf tee exhaust mod"

[studio54]

Originally Posted by relative4

Google "bmw golf tee exhaust mod"

It's not that cause i have the BMW performance muffler which does not have a flap. Also the exhaust in the video is a BMW performance muffler.

[studio54]

sorry to bump, but i am curious about that

[Saif2018]

Originally Posted by studio54

Hello,

I don't know if it's because i am full catless now but i noticed when i blip the throttle that my exhaust does a sound similar (to my ears) to wastegate rattle.

It's just when you are stationnary, and you blip the throttle, when rpm fall next to idle, let's say from 750rpm to 650rm, very short range like a half second, it does a rattle snake zzzzz sound.

I believed at first and was afraid (new turbos) it could be wastegate rattle again, but i does sound the same with wastegate open, and this sound is shorter than infamous wg rattle. It's probably a normal sound that most exhaust does, and it's probably more audible when you are catless.

I can't find online how it's called? on my car it's very audible in indoor parkings.

I find some sound clip online of 128i to make sure it's not wastegate rattle cause 128i engines don't have turbos :

https://www.youtube.com/watch?v=IX7cpS2nFdo at 10 seconds, at 14 seconds [...] and so on.

It's this exact sound. Anyone what causes this sound and how it's called?

I do not particulary like this sound, what can i do to reduce this? resonators ?

Thanks !!

The exhaust needs to be properly checked, could be blown or something else loose that's causing the buzzing sound.

Can post a video of your exhaust?

[studio54]

Originally Posted by Saif2018

The exhaust needs to be properly checked, could be blown or something else loose that's causing the buzzing sound.

Can post a video of your exhaust?

I have no video for now but i can make it.

But there are dozens videos of this buzzing sound on 335i, 135i, 128i, 330i and so on on Youtube, almost all of them does this sound :

330i : https://www.youtube.com/watch?v=gSBxCLGeAok at 40 seconds

Even this Corvette https://www.youtube.com/watch?v=hGqO8rUka3E at 40 seconds too

Maybe it's a normal sound that exhaust does when RPM goes back to idle?

[Saif2018]

Originally Posted by studio54

I have no video for now but i can make it.

But there are dozens videos of this buzzing sound on 335i, 135i, 128i, 330i and so on on Youtube, almost all of them does this sound :

330i : https://www.youtube.com/watch?v=gSBxCLGeAok at 40 seconds

Even this Corvette https://www.youtube.com/watch?v=hGqO8rUka3E at 40 seconds too

Maybe it's a normal sound that exhaust does when RPM goes back to idle?

The 330i sounds normal, I can hardly hear any buzzing sound.

The previous one posted had a distinct buzzing sound

[studio54]

Originally Posted by Saif2018

The 330i sounds normal, I can hardly hear any buzzing sound.

The previous one posted had a distinct buzzing sound

Really, at between 40 & 45 seconds on the first video (330i) you can't hear the buzzing sound ?

[Saif2018]

Originally Posted by studio54

Really, at between 40 & 45 seconds on the first video (330i) you can't hear the buzzing sound ?

Just listened to it again, can't really hear any buzzing sound like yhe previous post 🤷

[studio54]

Originally Posted by Saif2018

Just listened to it again, can't really hear any buzzing sound like yhe previous post 🤷

ok weird or maybe we do not speak about the same sound lol, i would have said that the noise/flutter is even louder than in the first post video, it should be normal, i really wonder what is causing this sound.

[Saif2018]

Originally Posted by studio54

ok weird or maybe we do not speak about the same sound lol, i would have said that the noise/flutter is even louder than in the first post video, it should be normal, i really wonder what is causing this sound.

Post a video clip of your N54, that should give a better idea. Comparing to a 330i is not really gonna give you an idea, especially since the engine and exhaust system is different.

[studio54]

Originally Posted by Saif2018

Post a video clip of your N54, that should give a better idea. Comparing to a 330i is not really gonna give you an idea, especially since the engine and exhaust system is different.

I will when possible but N54s does have the sound aswell, i posted the 128i or 330i just to exclude wastegate argument
I am not saying it has a problem or something and it's not especially about my car, it's a general question i am asking, i just want to know what is causing this very short flutter effect when RPM drops back near to idle.
It's audible on most aftermarket exhaust clips.

[Saif2018]

Originally Posted by studio54

I will when possible but N54s does have the sound aswell, i posted the 128i or 330i just to exclude wastegate argument
I am not saying it has a problem or something and it's not especially about my car, it's a general question i am asking, i just want to know what is causing this very short flutter effect when RPM drops back near to idle.
It's audible on most aftermarket exhaust clips.

Usually it's either wastegate rattle or rattle from the flap,

Are you sure the M performance exhaust has no flaps in the exhaust to close the exhaust on one side?

[studio54]

Originally Posted by Saif2018

Usually it's either wastegate rattle or rattle from the flap,

Are you sure the M performance exhaust has no flaps in the exhaust to close the exhaust on one side?

On mine, it's the BMW PE exhaust for N54 135i, and it doesn't have a flap, but maybe the M performance has one ? And maybe it's different on the 335i version?

Here a video where it's really really audible, you can hear the rattlesnake when he blip the throttle at 16 seconds, at 18 seconds, at 20 seconds.... and then you can hear litterally for 4 seconds at the end of the video between 1m16 and 1m20.

https://www.youtube.com/watch?v=AwQ8kxTfQVA

As it's the V8 M3 e92, it does not have turbos, so no wastegates, and no flap. What's this sound ? Vibrations? Air back flow? As it's the seller/fabricant of this exhaust posting the video, i guess it's a normal sound...

[Saif2018]

Originally Posted by studio54

On mine, it's the BMW PE exhaust for N54 135i, and it doesn't have a flap, but maybe the M performance has one ? And maybe it's different on the 335i version?

Here a video where it's really really audible, you can hear the rattlesnake when he blip the throttle at 16 seconds, at 18 seconds, at 20 seconds.... and then you can hear litterally for 4 seconds at the end of the video between 1m16 and 1m20.

https://www.youtube.com/watch?v=AwQ8kxTfQVA

As it's the V8 M3 e92, it does not have turbos, so no wastegates, and no flap. What's this sound ? Vibrations? Air back flow? As it's the seller/fabricant of this exhaust posting the video, i guess it's a normal sound...

The M3 sounds perfectly normal to me.

I've got a 2007 335i M Sport, pretty sure most if not all N54 exhaust systems have flaps that close off one of the pipes, this often rattles and usually fixed easily with Golf T mod.

Have you had the exhaust system properly inspected?

[studio54]

Originally Posted by Saif2018

The M3 sounds perfectly normal to me.

I've got a 2007 335i M Sport, pretty sure most if not all N54 exhaust systems have flaps that close off one of the pipes, this often rattles and usually fixed easily with Golf T mod.

Have you had the exhaust system properly inspected?

So i guess my car sounds perfectly normal as well but you don't hear the small rattlesnake at all ? I isolated it here with audacity :

https://vocaroo.com/9CSCYIBaypC

Just wonder what is causing this sound effect.

Yep N54 stock muffler has flaps but concerning the PE (Performance Exhaust) it's the aftermarket exhaust sold by BMW, it gets rid of the flap, at least for the 135i.

[Saif2018]

Originally Posted by studio54

So i guess my car sounds perfectly normal as well but you don't hear the small rattlesnake at all ? I isolated it here with audacity :

https://vocaroo.com/9CSCYIBaypC

Just wonder what is causing this sound effect.

Yep N54 stock muffler has flaps but concerning the PE (Performance Exhaust) it's the aftermarket exhaust sold by BMW, it gets rid of the flap, at least for the 135i.

If your logs look fine, I wouldn't worry about it to be honest. It's so minor if anything anyway.

[studio54]

I was reading this thread about the exact same noise: https://www.1addicts.com/forums/show....php?t=1009862

and i tend to believe now that some people (including me ) confused at some point the infamous wg rattle sound with the normal exhaust sound (rrrr) it does when rpm fall down...

and realizing it's easy to be misleaded, for example this video on YT, which title is "wastegate rattle" where it's not :

https://www.youtube.com/watch?v=gusKgaWnAdM

[Saif2018]

Originally Posted by studio54

I was reading this thread about the exact same noise: https://www.1addicts.com/forums/show....php?t=1009862

and i tend to believe now that some people (including me ) confused at some point the infamous wg rattle sound with the normal exhaust sound (rrrr) it does when rpm fall down...

and realizing it's easy to be misleaded, for example this video on YT, which title is "wastegate rattle" where it's not :

https://www.youtube.com/watch?v=gusKgaWnAdM

Exhaust rattle is often mistaken for WG rattle, that's true.