I removed my airpump+acv and installed blockoff plates on both the acv location and the outside of the LIM where the two pipes attached. I still get this whiny moo sound sometimes between 2000-2500 rpms though. It's not the same moo sound when the airpump is not muffled but rather its more high pitched and quieter. I hope I made myself somewhat clear but it's hard to describe the sound. Has anyone had a similar problem on their car?

 

If you have a loose or split silicone coupler it can squeal - like letting air out of a balloon though more than a moo, at least in my experience...

 

you have an aftermarket dual intake, like an HKS?

 

Couldn't this be the dual intake moo-cow noise? I haven't dealt with this stuff in a while but this reminds me of that

 

checked the hoses I could see without removing the uim and everything looked good. As for the intake, I am using ebay hard pipes with K&Ns. The stock bovs are vented to the atmosphere and the pipes for the airpump/acv are removed. It's weird the sound only happens every once in a while.

 

try removing the intake temporarily and run the car. if it doesnt make the noise then you've found your problem. i dont recommend driving around without filters, but in your driveway its totally fine....unless you have the gardeners over with their dustblowers.

 

If you're just venting the bov and abv then that could be the source of the noise. When the valve(s) open slightly they could certainly resonate and make noise. I would check them per FSM to ensure they are sealing properly. A leaky one could squeal.

As an aside, I don't know if those are designed to hold vacuum, and could potentially take unfiltered air in if you're just venting them... there's a reason they are originally routed to the factory air box, either for noise or for filtering.

 

Does anyone have this sound with the pettit intake and a solution to get rid of it? This is the pettit with two big filters, one smaller, heat shield, and this plastic tube.

I checked out these threads:

https://www.rx7club.com/showthread.p...t=intake+noise

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/moowing-sound-so-bad-104522/

And they mention the pettit comes with silencers. They are two black things in series on a clear hose that vents straight down, I can see them on mine. (Circled in red in the pic, excuse the mess) Either i've got another problem or they aren't working. On the highway between 2-3k in 5th i've got a horrible howling noise, worse at partial/no throttle. Trans has been rebuilt and diff was replaced with a kaaz so i've ruled those out. Thanks for any ideas.

 

really sorry to beat a dead horse. just one bump to see if anyone can comment.