Strange "roaring" sound coming from little box...

[Sygerwulf]

There's a funny roaring sound coming from the hose that connects the airbox to the little black box next to the power steering resovoir. Since my wreck I haven't been able to use the stock airbox so I have a cone filter installed and I put a little breather filter on the hose going to the little box. This was a couple years ago *hey, I have a kid and i'm broke*

Lately I've noticed that after it's been started and idled for a couple minutes it'll start making a light roaring sound. If it rev it at all it stops, then after a few seconds starts up again. Anyone have any idea what's causing this?

And wtf is this little box anyway? I heard it had something to do with the exhaust but never looked into it farther.

[benemorius]

Knowing what car it is would help, but it seems to fit the anatomy of a dohc 240.

Sounds like you're talking about the aiv. I've never heard one roar, but they go bad all the time. If it is confirmed that you are in fact dealing with the aiv on a 240, search the board for "aiv remove". Everyone and their grandmother's parakeet just removes it - frequently even if it's not causing any problems at all.

[NISTECH]

I still have mine

You probably have a bad reed valve. [ the metal thing with a gold saucer on it below the mystery box]

It is used to add oxygen to the exhuast when its cold. It creates a hotter fire to warm the car up faster and gets the cat to operating temp faster to help control emissions earlier. Once the car is warmed up it is none functional as far as emissions use.

Like he said most just remove it and plug off the air line. If you live in a visual smog inspection state you may want to at least retain the parts for installation during smog tests.