Flutter/Rattle Sound With Moderate Throttle

Eja144 · 06-27-2020, 07:33 PM

I had been trying to troubleshoot this noise that was driving me absolutely insane for the last several months. It's somewhere between a flutter and a rattle – at times sounding like some kind of airflow leak and other times more metallic. I thought it was coming from around the driver's side front cat.

Fast-forward to about 3 weeks ago, I brought the car in for some maintenance/service – new battery, valve cover gaskets, rear tires, some other small stuff. The shop diagnosed the noise as coming from the gasket between the headers and primary cats (which after researching, seems like a somewhat common failure point on these cars). The car sounded/felt fantastic when I picked it up and for about a week after, at which point the noise started gradually returning.

It's now louder than it's ever been, and I feel it's affecting the performance of the car. Throttle response seems a little sluggish – especially at lower RPMs, idle isn't quite as smooth, "hiccups" a bit on cold start.

The obvious hypothesis is that it was in fact the gaskets, and for some reason the new ones sprung a leak. But, I wanted to post here to see if anyone's had a similar experience and can confirm I'm on the right track.

A few observations:

Noise starts with about 30% throttle in any gear
Any RPM, but most pronounced between 2k and 4k
Becomes loudest at about 50% throttle, then tapers off a bit at WOT
Seems to get louder and come on with less throttle the warmer the car gets - it will be more pronounced at the end of a drive than it was at the beginning

Finally, I drove up on ramps today to investigate and took a few videos. Driver side seemed notably noisier when cold.

Driver Side - Cold Start:

Passenger Side - Cold-to-Warm:

Driver Side - Warm:

SwagMuffin · 06-27-2020, 08:59 PM

I also have a fluttering noise when I'm cruising in low rpm, but it's extremely quiet at idle. Curious to see if it's my donut gaskets at the header/cats. I had a shop tell me it was coming from my acm muffler mod, but looking for a second opinion as I can almost hear something under my seat below 3k, anything above that sounds normal. I've never heard of an oem muffler mod going bad. Hopefully someone could chime in before I tell a muffler shop to open up my oem muffler to check welds. When you replaced your x pipe, was a new donut gasket installed? I'm on oem x pipe and it was never removed from the car. My throttle is also sluggish, it's gotten to the point where I hate driving my car cause it sounds like trash. The sound is so embarrassing and pronounced going uphill

Eja144 · 06-27-2020, 10:49 PM

Quote:

Originally Posted by SwagMuffin

I also have a fluttering noise when I'm cruising in low rpm, but it's extremely quiet at idle. Curious to see if it's my donut gaskets at the header/cats. I had a shop tell me it was coming from my acm muffler mod, but looking for a second opinion as I can almost hear something under my seat below 3k, anything above that sounds normal. I've never heard of an oem muffler mod going bad. Hopefully someone could chime in before I tell a muffler shop to open up my oem muffler to check welds. When you replaced your x pipe, was a new donut gasket installed? I'm on oem x pipe and it was never removed from the car. My throttle is also sluggish, it's gotten to the point where I hate driving my car cause it sounds like trash. The sound is so embarrassing and pronounced going uphill

My exhaust system is totally stock, so no aftermarket x-pipe, but the shop did replace both OEM donut gaskets. It fixed the sound completely for about a week. I was so happy - the car sounded and felt the way it was meant to - smooth and powerful. Now it's back to sounding like a janky old Hyundai. I just can't imagine that brand new gaskets went bad that quickly. I'm wondering if heat expansion possibly caused one to shift and break its seal. Or perhaps the sound is something entirely different.

Pig Farmer · 06-28-2020, 10:50 AM

Just a thought... the nuts that bolt the x-pipe to the header are made form some types of copper alloy. I wonder if the threads on the nuts are letting go causing an exhaust leak?

BTW, can you check your codes? An exhaust leak between the headers and cat can appear as a lean condition to the primary O2 sensor. The car will attempt to correct the lean condition by running rich, hence the poor performance. The codes may tell you which bank has the leak.

SwagMuffin · 06-28-2020, 12:20 PM

I'm going to replace the OEM gaskets. It's worth a try since mine has 70k on them. I have no codes, just the weird sound in low rpm.

Eja144 · 06-28-2020, 12:23 PM

Quote:

Originally Posted by SwagMuffin

I'm going to replace the OEM gaskets. It's worth a try since mine has 70k on them. I have no codes, just the weird sound in low rpm.

Definitely worth a shot. I'm interested to see if it fixes the noise for you, and if so, how long it lasts.

Eja144 · 06-28-2020, 03:41 PM

Quote:

Originally Posted by Pig Farmer

Just a thought... the nuts that bolt the x-pipe to the header are made form some types of copper alloy. I wonder if the threads on the nuts are letting go causing an exhaust leak?

BTW, can you check your codes? An exhaust leak between the headers and cat can appear as a lean condition to the primary O2 sensor. The car will attempt to correct the lean condition by running rich, hence the poor performance. The codes may tell you which bank has the leak.

That's a good thought. I might try to get back under the car and see if I can feel any gases escaping near those bolts.

Oddly enough, no codes being thrown, other than a right tail light bulb which I fixed a few days ago.

Eja144 · 07-10-2020, 04:15 PM

Following up on this one... turned out the new donut gasket on the driver side blew out. New gasket installed, car sounds great again. Crossing my fingers that this one lasts.

Zeesh89 · 01-31-2021, 10:27 AM

Hi All,

Was hoping someone could help me with a similar problem. On my e92 m3, when accelerating very gently (between 1-2k RPM, I hear this little jingle sound that is coming from underneath the car, almost underneath the drivers seat. The sound can be heard on the video posted below at around 10 seconds in (you have to listen carefully to catch it). It literally sounds like a little tambourine is being shaken and I have to drive with the windows down to hear it.
I did alot of reading around on this and it seems to me like there are several potential culprits: donut gasket that connect some exhaust pipes, a bracket that's loose, a mounting thats loose, heat shield (though my mechanic confirmed no issues with this).
The cars performance is generally ok, a little bit sluggish at times but I'm not a fast driver (lots of speed restrictions where I live).

I'd be very grateful if anyone can advise.
Thank you.

shyterence · 02-16-2021, 02:38 AM

Hi Zeesh89,

My M3 E90 has the same noise.
It is now under checking by the dealer.

Let's exchange information if there is any findings.

Regards,
Terence

Zeesh89 · 03-20-2021, 10:04 AM

Thanks shyterence......would be great if the dealer could pin point what it is.... my mechanic has looked several times and still can't put his finger on the cause.

Many thanks

Redd · 03-20-2021, 10:09 AM

Quote:

Originally Posted by Zeesh89

Hi All,

Was hoping someone could help me with a similar problem. On my e92 m3, when accelerating very gently (between 1-2k RPM, I hear this little jingle sound that is coming from underneath the car, almost underneath the drivers seat. The sound can be heard on the video posted below at around 10 seconds in (you have to listen carefully to catch it). It literally sounds like a little tambourine is being shaken and I have to drive with the windows down to hear it.
I did alot of reading around on this and it seems to me like there are several potential culprits: donut gasket that connect some exhaust pipes, a bracket that's loose, a mounting thats loose, heat shield (though my mechanic confirmed no issues with this).
The cars performance is generally ok, a little bit sluggish at times but I'm not a fast driver (lots of speed restrictions where I live).

I'd be very grateful if anyone can advise.
Thank you.

My money is something exhaust related. If you've already checked all the heat shields and it's not those, get under the car and give your exhaust, cats, muffler a good whack with your hands and see if anything is loose inside. My guess is you have a broken cat, mounting or a bad weld somewhere.

Zeesh89 · 04-09-2021, 03:14 AM

Thanks Redd

My mechanic had a knock around there a few times but couldn't see anything loose - he also had a knock around on the cat but didn't notice or hear anything loose there either.

Hi Terence, did you manage to make any progress with the dealer?

renaissance · 05-03-2021, 05:12 PM

Quote:

Originally Posted by Zeesh89

Thanks Redd

My mechanic had a knock around there a few times but couldn't see anything loose - he also had a knock around on the cat but didn't notice or hear anything loose there either.

Hi Terence, did you manage to make any progress with the dealer?

I had this noise too. Only in D and R around 1~2K rpm.

According to this thread, that noise comes from leaked emission valve.

https://www.m3post.com/forums/showpo...&postcount=213

renaissance · 05-03-2021, 11:08 PM

Quote:

Originally Posted by renaissance

I had this noise too. Only in D and R around 1~2K rpm.

According to this thread, that noise comes from leaked emission valve.

https://www.m3post.com/forums/showpo...&postcount=213

To change the valve is not an easy job because of its location!

https://www.m3post.com/forums/showthread.php?t=1247529

Zeesh89 · 05-04-2021, 09:54 PM

Hi Renaissance

Thanks alot for coming back on this one.
Are there any other videos that post the sound/rattle that I'm having to be 100% this could be the problem. Just want to be sure before my indy starts any work....sounds like its not a quick job and will cost a fair bit of money too.

Any further thoughts are greatly appreciated.

Thanks
Zee

renaissance · 05-04-2021, 10:30 PM

Quote:

Originally Posted by Zeesh89

Hi Renaissance

Thanks alot for coming back on this one.
Are there any other videos that post the sound/rattle that I'm having to be 100% this could be the problem. Just want to be sure before my indy starts any work....sounds like its not a quick job and will cost a fair bit of money too.

Any further thoughts are greatly appreciated.

Thanks
Zee

Hi Zee,

Here are my recorded video.

Zeesh89 · 05-05-2021, 04:46 AM

Yep
That definitely resembles the rattle sound I am having. Sounds almost the same in the car park videos. I'm very glad you were able to show this as I was clueless about it for too long.

Lets see what the indy says in terms of repair cost.

Thanks alot once again for sharing this.

Did you have yours emission valves changed too ?

renaissance · 05-05-2021, 06:08 AM

Quote:

Originally Posted by Zeesh89

Yep
That definitely resembles the rattle sound I am having. Sounds almost the same in the car park videos. I'm very glad you were able to show this as I was clueless about it for too long.

Lets see what the indy says in terms of repair cost.

Thanks alot once again for sharing this.

Did you have yours emission valves changed too ?

Hi Zee,

I had that issue for quite a long time but just can't confirm what cause it until I saw that post.

I haven't fixed it yet

Zeesh89 · 05-05-2021, 11:45 AM

haha ok cool.

It's such an embarrassing noise...especially driving down a quiet road..... totally not how a M3 should sound. My mechanic has quoted me roughly £400/500 in labour to do the job.

renaissance · 05-07-2021, 09:39 PM

Quote:

Originally Posted by Zeesh89

haha ok cool.

It's such an embarrassing noise...especially driving down a quiet road..... totally not how a M3 should sound. My mechanic has quoted me roughly £400/500 in labour to do the job.

Hi Zee,

I had private discussion with "saxodreng" who has leaked emission valve during these days. He told me that mine doesn't sounds like the issue he had. He said that "leaked emission valve" just like the hoarse sound from the cold start period.

He suggested "check hoses to induction system".

pp276 · 05-28-2021, 07:10 AM

Zee, your video is the exact sound I've have for last 5 years of ownership! It's been hard to make a recording as seems to come and go but always at low speeds under light throttle, for example, up parking ramps or in stop-start traffic. Really embarrassing but does not seem to affect how the car drives.

I've had it checked by 3-4 mechanics, including a thorough look at my stock exhaust, with no joy.

I'd be very interested in any progress you guys make!!

06-27-2020, 07:33 PM	#1
Eja144 Second Lieutenant 303 Rep 298 Posts Drives: 2008 E90 M3 Join Date: Jun 2019 Location: Long Island, NY iTrader: (0)	Flutter/Rattle Sound With Moderate Throttle I had been trying to troubleshoot this noise that was driving me absolutely insane for the last several months. It's somewhere between a flutter and a rattle – at times sounding like some kind of airflow leak and other times more metallic. I thought it was coming from around the driver's side front cat. Fast-forward to about 3 weeks ago, I brought the car in for some maintenance/service – new battery, valve cover gaskets, rear tires, some other small stuff. The shop diagnosed the noise as coming from the gasket between the headers and primary cats (which after researching, seems like a somewhat common failure point on these cars). The car sounded/felt fantastic when I picked it up and for about a week after, at which point the noise started gradually returning. It's now louder than it's ever been, and I feel it's affecting the performance of the car. Throttle response seems a little sluggish – especially at lower RPMs, idle isn't quite as smooth, "hiccups" a bit on cold start. The obvious hypothesis is that it was in fact the gaskets, and for some reason the new ones sprung a leak. But, I wanted to post here to see if anyone's had a similar experience and can confirm I'm on the right track. A few observations: Noise starts with about 30% throttle in any gear Any RPM, but most pronounced between 2k and 4k Becomes loudest at about 50% throttle, then tapers off a bit at WOT Seems to get louder and come on with less throttle the warmer the car gets - it will be more pronounced at the end of a drive than it was at the beginning Finally, I drove up on ramps today to investigate and took a few videos. Driver side seemed notably noisier when cold. Driver Side - Cold Start: Passenger Side - Cold-to-Warm: Driver Side - Warm:
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06-27-2020, 08:59 PM	#2
SwagMuffin Private First Class 17 Rep 110 Posts Drives: E90 M3 Join Date: Jun 2017 Location: San Francisco iTrader: (2)	I also have a fluttering noise when I'm cruising in low rpm, but it's extremely quiet at idle. Curious to see if it's my donut gaskets at the header/cats. I had a shop tell me it was coming from my acm muffler mod, but looking for a second opinion as I can almost hear something under my seat below 3k, anything above that sounds normal. I've never heard of an oem muffler mod going bad. Hopefully someone could chime in before I tell a muffler shop to open up my oem muffler to check welds. When you replaced your x pipe, was a new donut gasket installed? I'm on oem x pipe and it was never removed from the car. My throttle is also sluggish, it's gotten to the point where I hate driving my car cause it sounds like trash. The sound is so embarrassing and pronounced going uphill
	Appreciate 0 Quote

06-28-2020, 10:50 AM	#4
Pig Farmer Major 340 Rep 1,293 Posts Drives: E92M Join Date: May 2010 Location: Florida iTrader: (0)	Just a thought... the nuts that bolt the x-pipe to the header are made form some types of copper alloy. I wonder if the threads on the nuts are letting go causing an exhaust leak? BTW, can you check your codes? An exhaust leak between the headers and cat can appear as a lean condition to the primary O2 sensor. The car will attempt to correct the lean condition by running rich, hence the poor performance. The codes may tell you which bank has the leak.
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06-28-2020, 12:20 PM	#5
SwagMuffin Private First Class 17 Rep 110 Posts Drives: E90 M3 Join Date: Jun 2017 Location: San Francisco iTrader: (2)	I'm going to replace the OEM gaskets. It's worth a try since mine has 70k on them. I have no codes, just the weird sound in low rpm.
	Appreciate 1 Eja144303.00 Quote

07-10-2020, 04:15 PM	#8
Eja144 Second Lieutenant 303 Rep 298 Posts Drives: 2008 E90 M3 Join Date: Jun 2019 Location: Long Island, NY iTrader: (0)	Following up on this one... turned out the new donut gasket on the driver side blew out. New gasket installed, car sounds great again. Crossing my fingers that this one lasts.
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01-31-2021, 10:27 AM	#9
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	Hi All, Was hoping someone could help me with a similar problem. On my e92 m3, when accelerating very gently (between 1-2k RPM, I hear this little jingle sound that is coming from underneath the car, almost underneath the drivers seat. The sound can be heard on the video posted below at around 10 seconds in (you have to listen carefully to catch it). It literally sounds like a little tambourine is being shaken and I have to drive with the windows down to hear it. I did alot of reading around on this and it seems to me like there are several potential culprits: donut gasket that connect some exhaust pipes, a bracket that's loose, a mounting thats loose, heat shield (though my mechanic confirmed no issues with this). The cars performance is generally ok, a little bit sluggish at times but I'm not a fast driver (lots of speed restrictions where I live). I'd be very grateful if anyone can advise. Thank you.
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02-16-2021, 02:38 AM	#10
shyterence Registered 0 Rep 2 Posts Drives: BMW M3 E90 Join Date: Feb 2021 Location: Hong Kong iTrader: (0)	Hi Zeesh89, My M3 E90 has the same noise. It is now under checking by the dealer. Let's exchange information if there is any findings. Regards, Terence
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03-20-2021, 10:04 AM	#11
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	Thanks shyterence......would be great if the dealer could pin point what it is.... my mechanic has looked several times and still can't put his finger on the cause. Many thanks
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04-09-2021, 03:14 AM	#13
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	Thanks Redd My mechanic had a knock around there a few times but couldn't see anything loose - he also had a knock around on the cat but didn't notice or hear anything loose there either. Hi Terence, did you manage to make any progress with the dealer?
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05-04-2021, 09:54 PM	#16
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	Hi Renaissance Thanks alot for coming back on this one. Are there any other videos that post the sound/rattle that I'm having to be 100% this could be the problem. Just want to be sure before my indy starts any work....sounds like its not a quick job and will cost a fair bit of money too. Any further thoughts are greatly appreciated. Thanks Zee
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05-05-2021, 04:46 AM	#18
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	Yep That definitely resembles the rattle sound I am having. Sounds almost the same in the car park videos. I'm very glad you were able to show this as I was clueless about it for too long. Lets see what the indy says in terms of repair cost. Thanks alot once again for sharing this. Did you have yours emission valves changed too ?
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05-05-2021, 11:45 AM	#20
Zeesh89 New Member 4 Rep 17 Posts Drives: BMW M3 E92 Join Date: Jan 2021 Location: London iTrader: (0)	haha ok cool. It's such an embarrassing noise...especially driving down a quiet road..... totally not how a M3 should sound. My mechanic has quoted me roughly £400/500 in labour to do the job.
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05-28-2021, 07:10 AM	#22
pp276 Registered 0 Rep 1 Posts Drives: M3 e92 Join Date: Sep 2016 Location: Australia iTrader: (0)	Zee, your video is the exact sound I've have for last 5 years of ownership! It's been hard to make a recording as seems to come and go but always at low speeds under light throttle, for example, up parking ramps or in stop-start traffic. Really embarrassing but does not seem to affect how the car drives. I've had it checked by 3-4 mechanics, including a thorough look at my stock exhaust, with no joy. I'd be very interested in any progress you guys make!!
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