My AEM has a short hose fitting that goes to the valve cover. There is another fitting and hose that goes down by the TB and then back toward the rear? What is this hose for? It provides a vacuum source for something from the intake pipe?

 

Alot of people plug that one off on the intake, and on the hose itself in the engine bay. Methinks its just another cause for oil to get into your intake, or sponge if you have the stock airbox.

 

Like LilSpark said, It's cool to hook it up if you have the stock intake, - it is just plumbed to the airbox outside of the filter. Open it up and Voila oil dripping from a sponge.

If you have the aem intake, definitely don't hook it up to that line; it will spill oil directly into your intake tube and more importantly, your turbo. In your turbo it will cook and burn, and coat the wheels(bad).
I wouldn't just cap the nipple on the engine...it is your crankcase breather and has a purpose...to extract hot gasses. But we are trying not to introdce hot gasses to the intake, plus turbulence is bad.
Just run it from the crankcase vent to an air breather and cap the nipple on the intake. Maybe put a sock on the breather to soak up any oil that eventually might come out.

 

I wasn't referring to the hose that connects to the valve cover. The other longer hose that goes to ???

 

Oh - you mean the black vaccum line I guess - sorry. A lot of people just plug it - it is essentially a small boost leak. It is there as part of the evaporative emmissions system or something, to keep the tank from possibly pressurizing, but many feel it is wholly unimportant. Some engineers will argue to the contrary and a few people in the know have sided with them, but I can say that it made a little bit of a difference for me.

 

i was wondering about that line as well.if you were to plug the part on the intake, what do you do with the other side?will it affect it in any way?boost leak before pluggin it or after?

 

plug both to stop leak. It is there hooked up or not.

 

double post - my mistake.

 

Yeah thats the hose I was talking about, the longer one. Everyone just plugs both lines.

 

OK.......I was gonna cap the black vac line but i cant really tell where it runs to, it looks like it goes behind the battery.If i take out the battery will i be able to get to it?if not whats the easiest route?also the line that runs from the valve cover to the intake,would i be able to cap the intake side and run a vac. line with a breather for the valve cover side? thanx in advance