what does the hose actually do?

[S13inBatnRuge]

In the hose i have outlined, can I remove this and put a breather filter in its place. I know it kind dark in the photo but its not mine just the best I could find online in a flash.

thanks in advance. http://nissaninfiniticlub.net/...r.JPG

[OldmanPurdy]

Im pretty sure that hose is to allow oil to recirculate into the intake manifold at high RPM's. im not sure about a breather filter but you can put an oil catch can on it with collects all the oil that comes out.

[Chezedik]

Nope, just a breather to release crankcase blow-by pressure back into the intake tract. It is strictly for emissions. The idea is that any air that passes by the piston rings could contain unburnt fuel. That said, if it vented to the air, it would release these unburnt hydrocarbons to the air, causing pollution. The problem is that it pollutes your intake with oil and carbon, so most people remove them and install a breather filter.

[S13inBatnRuge]

so i got the right idea... cool

[Chezedik]

Yeah, you're cool, so long as you cap off the line on the intake side. If you do not, the car will run lean and loose power. It could also buck or hesitate. This is because it is not being read by the MAF.