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Discussion Starter · #1 ·
Wish I was talking about the BPV/BOV...

Anyway, I noticed this a week or two ago. I was driving in second and when to shift at around 2500 - 3000 RPM. As I let off the gas, I heard a noise from the driver side, kind of in the direction of the clutch/brake pedal (well, somewhat under it?). Its like low grumbling "woo woo" whirling sound. Sometimes, I can feel it in the pedals, like something is spinning but rubbing up against something or like a bearing of some sort?

So what I've noticed:
  • Only happens around 2500-3000 rpm range, usually when I let off the gas (even when not shifting and just letting off gas) but I've sometimes encountered it try to go slowly through the 2500-3000 range (not sure if I'm subconsciously letting off the gas a bit to slow it down and thus causing the noise).
  • Only happens in gear, 1st, 2nd, and very lightly 3rd.
  • Does not happen when in neutral.
  • Definitely on the driver side, almost as if its in the direction of under the clutch and brake pedal area or maybe near to the wheels (always notice it the worst when I'm not actively trying to listen for it)
  • Very repeatable, just the intensity is somewhat random
  • Weird enough to instill some paranoia.

Anyway, so far, I've done to the car:
  • Hammer the crap out of the shift arm to get a shift plate in and then again to get it out (didn't like it and that roll pin was stubburn)
  • RMM (which I did retighten yesterday just to see if that was the culprit)
  • FMIC (Didn't recheck the bolts, but put my hand in to wiggle it and still seems secure and stable)
  • --Also with the FMIC, while the car was on the ground, I did turn the wheel to the left and right without turning it on if that matters or screwed something up
  • New Air box under tray (I stripped the bolts so I bought a new one and put it in)
  • Tightened back the lug nuts on my wheels to 100 ft/lbs.


And thats about it. Any ideas?
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Discussion Starter · #4 · (Edited)
I'll be more adamant on recording my driving. I have a dashcam but that is unable to pick up the sound. I actually got back from trying to record it with my phone by the pedals, but anything I could reproduce was drowned out by the regular sounds of the car.

Never even considered the sound symposer, but it could be. I never really messed with it. I'll fiddle with it when I get some time over the weekend.

For some reason, maybe it was that one time or so I swear I could feel it in the pedals, but the noise reminds me of something spinning/wobbling.

Anyway, thanks for the insights, I'll continue monitoring it.

[edit]
This doesn't quite sound right on video, but you can somewhat hear it at 13 seconds. Basically, all I do in this video is cruise a bit, then go up to 2500 or 3000rpm, then let off the throttle. I repeat this a few more times, but only the first one in this video picked up something weird. This was actually a 15 minute ride, but only this piece picked anything up. You also hear something at 23 seconds but I'm not sure if thats just my pedal squeaking. Every time after that, nothing out of the ordinary was picked up by the camera but it was still happening (not every time, but a lot when I got the rpms right).

 

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If it sounds acoustic, like fwu fwu

Does it happen when the BPV does not go?

Could be turbo fluttering, I have been hearing a lot of it recently
 

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Discussion Starter · #6 · (Edited)
Looked up some videos on how turbo flutters sounds on a FoST and it doesn't quite sound right. Similar in some aspects though. People tend to mention that they started getting turbo flutter after installing an intake, but all I have is a filter. I'll try putting the stock one back in over the weekend. I also can't really create the sound when not moving.

Thanks for the input. I'm waiting until the weekend when I have some free time to do more recording. I think I got it down as to how to create the sound. Start at 2000 rpm in 2nd gear. Moderately accelerate to 2500 rpms then slowly ease off while still pressing the gas so that you do eventually get to 3000rpm. You can hear it at 2700 while you're still slowly easing off. I'm putting in the OEM RMM over the weekend just to rule it out.

[edit]
Finally, the weekend!

So i'm home from work and waiting for my car to cool down a bit so I can check the FMIC mounting points. I did a search and came upon this:
http://www.focusst.org/forum/focus-st-performance/93601-cp-e-fmic-post-install-noise.html

Almost same exact thing and people seem to mention the same, turbo flutter. So, Ibepaintin, you are likely correct.

After checking my phone for my latest video (this time I count them so that I know when its happening, at 9, 15, and 24 seconds) and its almost similar to the video above.

Oh well, guess I'll just live with it.

Thanks everyone!
 
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