Fluttering Sound Between 2500-3000 rpm

[trey100]

Hi everyone.

I noticed this on my N55 335 as well so not sure if this is normal. I'm just noticing it now on my S55 F80 but it could very well have always been there.

It happens between 3rd gear and higher (mostly because rpm increase is slower) under load. So for instance say going up a hill in 3rd gear, Rpm currently at 2,200 rpm. Roll into the throttle and as the rpm passes 2,500 rpm, what sounds like a sheet of paper flapping in the wind sound comes in and lasts for about 500-750 rpm (may be longer but that's when you really notice it). Sound can also be similar to someone blowing into a spinning fan.

I've been doing some googling and can't see much except perhaps some folks experiencing this on other turbo models and pin pointing it to the diverter valve springs? Basically cracking open when it should be closed and leaking some boost?

Anyone come across this?

[BlatantMaple854]

Is this the sound you are hearing?

https://www.youtube.com/watch?v=EgU_yV3PYEE

[trey100]

Originally Posted by BlatantMaple854

Is this the sound you are hearing?

Nice find. Tough to tell but it is similar. Didn't see a diagnosis though. Went to BMW and of course it wasn't doing it. Not today. Googling I found people talking about something similar and they said perhaps the diverter valve gets stuck sometimes and let's some boost leak by. But like I said they didn't do anything. Car driving normal now.

I definitely noticed the same sound on my N55 335 when I had it. Not all the time in that case either.

[tebbnsx]

My car makes a noise like that when the AC is on and I’m accelerating. When it’s turned off there is nothing.

[BlatantMaple854]

Originally Posted by tebbnsx

My car makes a noise like that when the AC is on and I’m accelerating. When it’s turned off there is nothing.

Yup, that’s my original video. Tell your dealer that they need to add an additional weight to the low pressure line for the HVAC. Apparently it can rattle in a certain rpm range somewhere from the engine bay through the firewall.

[BlatantMaple854]

Originally Posted by trey100

Nice find. Tough to tell but it is similar. Didn't see a diagnosis though. Went to BMW and of course it wasn't doing it. Not today. Googling I found people talking about something similar and they said perhaps the diverter valve gets stuck sometimes and let's some boost leak by. But like I said they didn't do anything. Car driving normal now.

I definitely noticed the same sound on my N55 335 when I had it. Not all the time in that case either.

Run a test to see if the noise is only present when the AC is on. If so, take a look at my post above for the solution.

[trey100]

Originally Posted by BlatantMaple854

Run a test to see if the noise is only present when the AC is on. If so, take a look at my post above for the solution.

Thanks! I'll try it out.

[KeyBoy]

Originally Posted by trey100

Thanks! I'll try it out.

Did you ever get this resolved? Having same issue. Trying to get dealer to fix it but couldn't replicate the sound.

[White340]

Glad this was bumped. I also have the same sound. There is a weight that you put on the low pressure AC line that is supposed to fix this. It only happens with the AC on and under load. Makes the car sound like it's breaking down while accelerating.

I want to diy this as I don't want the dealer taking my car out for a joyride and it's a cheap part but I don't know where exactly the weight goes.

Can someone take a pic of the weight that the dealer added?

Thanks

[KeyBoy]

Originally Posted by White340

Glad this was bumped. I also have the same sound. There is a weight that you put on the low pressure AC line that is supposed to fix this. It only happens with the AC on and under load. Makes the car sound like it's breaking down while accelerating.

I want to diy this as I don't want the dealer taking my car out for a joyride and it's a cheap part but I don't know where exactly the weight goes.

Can someone take a pic of the weight that the dealer added?

Thanks

Yeah, it would be helpful to know how to access the low pressure AC line and where to actually clamp the weight on the hose.

Are you tuned? I notice the sound is more prevalent with a tune and more intermittent on stock tune.

[White340]

Originally Posted by KeyBoy

Yeah, it would be helpful to know how to access the low pressure AC line and where to actually clamp the weight on the hose.

Are you tuned? I notice the sound is more prevalent with a tune and more intermittent on stock tune.

Nope, fully stock

[KeyBoy]

Seems like F30 platform had same issue. Here's a pic of the second weight added (though not S55).

[White340]

Originally Posted by KeyBoy

Seems like F30 platform had same issue. Here's a pic of the second weight added (though not S55).

Thanks, s55 looks different. Can't find that hose. There was a TSB for this which I guess also has instructions if someone has access.

[KeyBoy]

Originally Posted by White340

Thanks, s55 looks different. Can't find that hose. There was a TSB for this which I guess also has instructions if someone has access.

Found this thread that I think shows where it is.


https://f80.bimmerpost.com/forums/sh....php?t=1381897

Both dealers I went to said there was no TSB for this issue which is unfortunate. For F30, there is.

[trey100]

Originally Posted by KeyBoy

Did you ever get this resolved? Having same issue. Trying to get dealer to fix it but couldn't replicate the sound.

It went away on its own. I had this same issue on my N55. It seems like something gets stuck and then just resets itself at some point.

[agustincuenca]

Thank god I found this thread. I have this exact same issue/flutter on my 2016 F80 M3 and as said before only happens when the AC is on and exactly between 2500 to 3000 RPMs. Did anyone found a DIY way to mitigate it or fix it?
If not, then I'll probably mention it when I bring the car in for the next oil change at the dealership.

[trey100]

Originally Posted by agustincuenca

Thank god I found this thread. I have this exact same issue/flutter on my 2016 F80 M3 and as said before only happens when the AC is on and exactly between 2500 to 3000 RPMs. Did anyone found a DIY way to mitigate it or fix it?
If not, then I'll probably mention it when I bring the car in for the next oil change at the dealership.

Mine seemed to go away on its own. Strange.

[Blazinskunk]

Just started hearing this on my 2018 M3. Does anyone know if the weight/clamp on the hose will resolve this?

[agustincuenca]

Originally Posted by Blazinskunk

Just started hearing this on my 2018 M3. Does anyone know if the weight/clamp on the hose will resolve this?

I'm planning on doing spark plugs soon and I will look into the AC hoses mentioned here while I have everything apart and will update here.

[DrewDDS]

https://www.ecstuning.com/b-genuine-...t/64539322952/

Here's the part. You have to take off your intercooler, then you can access the a/c line

[agustincuenca]

Originally Posted by DrewDDS

https://www.ecstuning.com/b-genuine-...t/64539322952/

Here's the part. You have to take off your intercooler, then you can access the a/c line

MVP, Thanks!

[White340]

Originally Posted by DrewDDS

https://www.ecstuning.com/b-genuine-...t/64539322952/

Here's the part. You have to take off your intercooler, then you can access the a/c line

Do you have a picture of exactly where it goes on this car? All I can find is a pic on the N55..