Need some help figuring out this noise

[WhiteVenom]

My car's been making this fluttering sound ever since I bought it last week. At first I thought it was the passenger side manifold to midpipe gasket leaking but I'm 90% sure it's not that now. To me it sounds like it's coming from the top of the motor, my dad thinks it's in the front, but it's hard to tell.

My theory at the moment is my IMRCs are stuck in a partially open position, letting the air flutter around them at certain RPMs. I'll havta look today while I'm driving to figure out what RPMs it does it most at.

Here's a couple videos of the noise
https://www.youtube.com/watch?v=Wlyf2eEhOhc

https://www.youtube.com/watch?v=uUWh9NLbUfs

 

[greenscobie86]

Hard to tell but it almost sounds like a tensioner/ACC pulley on the front. take the belt off and try it...

Or it might be the secondary chain guides, but it sounds a bit high pitched for that. Check the brackets on the motor as well(like coil brackets/EGR/etc..) to see if they might be resonating at a certain rpm.

Just my 0.02 cents.

 

[WhiteVenom]

You're right, it does sound like a tensioner/acc pulley, but I'm fairly sure it's not because it only does it between about ~2k and ~3-3200 rpm. This is another reason I believe it may be the IMRCs, I ran 3rd gear out some in the parking lot at work up to about 3500-3700 and then let it engine brake down. That fluttering stopped around 32-3300 when I was on the gas and once I let off it started around there and stopped around 2k.

As far as the chain guides, wouldn't that make noise pretty much all the time and (I would think) get worse/louder as the revs climbed? This noise never changes/pitch or gets louder/softer, it just starts and stops. Going to take the belt off one day this week and check for sure the pulleys, and definitely check brackets/etc. You could be on to something there ccasion14:

Will update my findings, any more suggestions are welcome and appreciated!

 

[MustangChris]

ill listen to the video after street outlaws. lol.

 

[MustangChris]

hm. im liking the IRMC's being stuck open/closed.... it sounds like they may be vibrating as air rushes past them and the trigger-box is trying to keep them closed or something.. ... . That's a very strange sound indeed!

 

[WhiteVenom]

ccasion14: Thanks for taking a look! That's my thinking too, I've never heard a leaky seal/gasket "flutter" like that.

I'm trying to decide what to do:
1) tear the intake down and just clean them/put them back together and hope they don't gum up/fail again
2) just unscrew the butterfly valves from the center rod, leaving the rod
3) buy the actual deletes. That's expensive tho, that's my least favorite, but will probably go this route because it's the right way to do it and I can port match to the intake/head and don't have to epoxy the rod holes shut.

It sucks tho cuz it's gonna havta wait a couple paychecks so I can get her tuned to compensate for the deletes, so I'll be a whistlin' SOB for a while lol