Weird hum/noise under acceleration

NOTE: I have transferred this thread which was created by me on another forum in hopes of helping someone else!


Hello fellow MSO'ers,
So I've been having a hard time with this weird hum noise under boosted acceleration on my '07 speed 3. I've got some mods done to it, but I have no idea what this sound could be. After doing some research on here, and via google I cannot seem to diagnose it. So I've decided to start a topic here with hopes that some of you could shed some light on my issue! I've posted a couple of videos of the sound. It should be noted that I am holding consistent boost pressures, as well as fuel pressures. I don't notice anything out of the ordinary with the things I am monitoring on my AP. There is no loss in power, or anything of that nature. I am wondering if my turbo is maybe going bad, anyways if anyone can help it would be seriously appreciated.

https://www.youtube.com/watch?v=xPrq...ature=youtu.be


https://www.youtube.com/watch?v=eVye...ature=youtu.be

I also would like to note that it also makes the sound when it is revved. Not just when it is under acceleration.

Alright everyone, so the NatorMN guys and I finally got an opportunity to take all the heat shields off, etc to take a look at the DP. Turns out the DP isn't loose. After further inspection while the car was running and I replicated the noise, we think that my exhaust manifold gasket may be bad, as there appeared to be some carbon build up on the mani bolts. As of yet, I haven't been able to replace the gasket but will be ordering it soon. Hopefully that will fix the issue.

SOLUTION:
Finally after being able to pull the manifold off, it turns out the fucking thing was cracked in half. I changed all my gaskets and put a new stock manifold on last night. Am finishing installing a new KO4 today, hopefully all problems solved.
Pics or it didn't happen right?




Other possibilities I tested prior to finding solution:
RE: "My 2012 made a similar noise when I broke one of the bolts off on the stock BPV and had to drive it 50 miles or so with one bolt, sounded like a clown blowing a horn, was quite amusing but loud as fuck.

Car ran decent with one bolt."

 

I had the same noise. It ended up being a slight slit had formed in a boost tube. Weird.