Flutter/Rattle Sound With Moderate Throttle

[Ajolives]

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 a very similar noise and thought it was a bad catalytic converter - ended up being bad exhaust gaskets (the donuts) and worn hardware.

When I inspected the noise it sounded like it was coming from inside the cat, and everything was tight, no rattles when I gave everything a shake. Thought it was a bad cat (125k miles) so I bought a aftermarket x-pipe and went to install.

There was basically nothing left of the drivers side gasket and the space between the pipes where the gasket should have filled was causing vibrations that would culminate near the cat. Or at least that was my conclusion. Haven't had the sound since and keep some backup parts in case it happens again.

Not saying it's your problem for sure, but if I were a betting man….

[Ximian]

Originally Posted by pp276

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!!

I've had this sound too for a while.

I've also had the codes 2739 and 27C5 that I attributed to the sensor/hose kit and the secondary air pump. I heard the next step for those codes is the secondary air valves and that makes sense with the noise I've been hearing at moderate throttle.

[Zeesh89]

Hi All

Thanks for your feedback.
I took it to another bmw specialist who told me it COULD be engine pinging (though that was a guess) ....from what I understood this comes down to carbon building up in the cylinders (or something like that) - i am not too technical with these things.

They also said they couldn't find any thing by doing an inspection.
Any thoughts from anyone else would he appreciated.

Many thanks and stay safe.

[DOCTOR.Y]

Do we have any finding? I have this noise also.

[SilverSlug]

I also have a similar noise, as well as the fluttering noise (especially at start up when the parts are cool and haven't expanded yet).

It finally got to a point where the Check Engine Light turned on and warning disclaimer for "Reduced Power" (limp mode).

[SilverSlug]

I assumed the leak was coming from the junction of the headers to the mid pipe as so many others have that same leak…

I had taken a rubber hose, and used it as a stethoscope to try to isolate the noise by sticking it around by that junction, and realized it definitely wasn't that.

I could clearly hear it coming from underneath the heat shield on the driver's side, and can only assume it's from the headers at the manifold.

Although perhaps it is the emission valve, and it just finally gave out all the way (or both).

I'll update what I find.

[shyterence]

Hi, I am still driving with the noise with me...can you guys solve the issue?

My mechanic told me the noise is related to carbon build up, so I leave it there...

[Zeesh89]

Reviving this Old thread in case anyone has experienced this issue as of late. The rattle seems to be quite obvious and is making the drive of the vehicle much less enjoyable

Thanks
Zeesh89