What's this hose/were's it go/why's it makeing noise?
 

OK, it's the pipe that is running up to the air filters from the side of the uper intake (it acctually goes under the upper intake) I have a set of apexi filter, and it is one of the three that goes to the upper filter. It's not the secondary turbo's BOV, and it's not the airpump intake hose.... It the last one on that.


What's it go to? Because when you rev the engine (just a little/alot) then snap the throttle closed, it sounds like my car has a friggen jake brake! It goes..... Bwwaaahhhhhhhh..... It sounds ALOT like a semi's engine brake!


Is there anyway to stop it? Also could it have anything to do with my car cutting out at .8 bar of boost? (or is that just fuel cut?)

sounds like the air pump hose.....the noise sounds like a loud mooooo!!!...lol....

Yeah, close enough :D


How do I stop it? I was searching, and found someone's post, and they said that had an insert that went in the airpumps inlet hose???

There is a hose that connects to the left-side of the airbox (right side if you're looking at it from the front of the car). It just makes a couple of bends and goes down beneath the airbox. Without this hose, you'll get the ugly sound on decel. With it, the sound disappears.

Take care,
Shad

That would be the air control valve pipe. Get some block-off plates and the noise will suddenly dissappear :)

Will it hurt anything to let it keep doing this? I'm assuming not, but it kind of paniced me when I first heard it.... thought I had like a speed thing (the movie), were if I got below 100 It rolls apex seals :D

The only reason it's making that noise now is because the stock airbox has a sectioned off portion that basically muffles this noise. It's not going to do any harm, it just sounds like shit. I took all my emissions off and i got the block off plate for that. My car doesn't make that sound anymore :D

You can insert a lawn mower muffler in the hose. It really cuts down on the noise. Home Depot sells mufflers for under$10.00.

Some aftermarket intakes provide an insert for that hose with a small (1/4") hole, basically a 1-hole stopper. Anyway, I created one of those, inserted it, packed the hose with steel wool, AND attached a small inline lawnmower muffler. Sounds like overkill, but that's what it took to quiet it down to my satisfaction.

Simply blocking it off would be hard on your airpump, disconnecting your airpump is hard on your cat, and removing your cat can cause boost creep. I decided to simply try to muffle it.

For future reference, just refer to it as the "moo hose" and everyone will know what you're talking about.

Agreed, that's why porting the wastegate, getting a MBC, a midpipe and eliminating the airpump all help :D