I pulled out the air box to do the air box mod and install boost controllers and i found this hose not connected to anything... What is it?

 

It's suppose to be like that.

 

really, all not connected to anything like that? what is it?

 

It's been 5 years since I've seen a stock airbox, but I imagine that's the airpump relief hose. It works similar to a BOV, releasing air from the airpump so it doesn't get overworked.

When using aftermarket open air intakes, that line has a tendancy to have a "MOOO" sound. So, in stock form, it defuses the sound through the airbox.

 

Yea that moo sound freaked me out when I installed my HKS intake, but then I was told its just the gremlins that haunt my car. No big deal

 

It's a funny sound. The Pettit intake has a "silencer" that replaces this. It's a clear hose that has a couple of plastic pieces hooked in-line. Almost completely eliminates the sound.

 

The air from the air control valve's relief comes back into the air box, passes through a muffler built into the airbox, then is vented out that tube. The tube also helps muffle the sound.

It's cool you actually have that whole hose - I've seen a few FD's that were either missing it, or missing half of it.

Dale

 

I was one of them .

If you're wondering what this diffuser/muffler looks like, just remove the upper half the intake box and youll see an enclosed chamber. Inside the chamber is a mesh-like sponge, then some netted wall, and then another spongy thing. Sounds weird but yeah thats your diffuser!

Jeremy