and what is its purpose? what does it do? thanks

circled in RED

 

Thats a filter, usually a tube would go back into the piping that attaches to the throttle body. The reason is so that vapors/blow-by get consumed by the motor and not go back into the environemnt. Usually that's illegal to just have it left unplugged (filter doesn't count as vapors would pass by).

 

just a breather

 

Bright red wireloom on sale, Aisle 5.

 

Is that your car? Are you looking into an oil catch can?

 

right next to the neon windshield wiper nozzles

 

Not OP's whip rather a whip hes getting ready to buy.

 

thats the crank-case breather filter. When you SC, you dont want boost pressure to go into the motor from there via the hose hooked to charge pipe. thats why some people let it breath through Atmosphere !

 

they are on BOGO now

 

The circled item is called a vacuum leak. There is a 3/8" rubber line that goes from Intake Manifold to the PCV Valve. The intent is pull vacuum from the crank case and valve covers. Since there is also a 3/8" rubber hose that connects the front/rear valve covers, a "breather" in the front valve cover is allowing the engine to pull un-metered air, and thus creating a vacuum leak, and likely a lean condition.

 

that probably explains why the manifold wasnt bolted down and i had this loud *** air leak whistling

 

Also the circled part will cause you to fail a smog check..

 

Hmmm, makes sense. A lot of people run breathers on them, including myself.
I have never noticed any issues, but what is your recommendation on this? Simply eliminate the filter and plug that port?

 

isn't that the purpose of the pcv valve?..to let air pass to the IM....it does'nt matter if fresh air is entering into the crankcase and valve covers thru that port because the IM is still going to pull it in and no matter how fresh(clean) it enters its still going to be splashed by oil because of the valvetrain

 

I was under the impression the reason WE (people running non OEM stillen chargepipe) leave it open because its bad for boost to go directly in from there... if you pay attention to the way OEM pipe is made, this is hooked up to all the way near the TB through T type connection

 

Yes, the purpose of the PCV is to allow air to sucked out of the valve covers and crank case. However, when you pop a breather filter, you are now sucking in air through it. Its fine to suck air through it, the problem is that its un-metered since its not going through the Mass Air Flow.

 

Correct, the OEM configuration does allow to suck air from two places, 1) PCV valve, 2) After the MAF. This is fine since all air sucked has already been metered.

The PCV valve is a check valve. It only allows vacuum to be pulled, but will not allow boosted air to enter the valve covers and crankcase. That's the reason why Stillen doesn't ask you to touch it when you install your SC.

 

On the stillen SC instructions, that port on the front valve cover gets routed back the SC air filter totally going around the MAF?

http://www.cardomain.com/ride/134522/1996-nissan-maxima

 

yup, avoids direct boost pressure. same boost leak at the end, lol