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Old 03-11-2011, 02:03 PM
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hose coming from front valve cover to throttle body

Old 03-11-2011, 02:06 PM
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vaccuum vent. i dont have my tube on there anymore. no issues.
Old 03-11-2011, 03:30 PM
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It's your clean air, positive crankcase vent.
It is need.
Old 03-11-2011, 03:47 PM
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i replaced the tube with a small filter.
Old 03-11-2011, 06:07 PM
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That will work
Old 03-11-2011, 06:11 PM
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Originally Posted by DavidGXP
It's your clean air, positive crankcase vent.
It is need.
That's what I thought.
Old 03-11-2011, 07:22 PM
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Now get a catch can for the dirty air side.

The stock system allows a bunch of oil to enter into the intake manifold. This effects airflow and pollutes the air/fuel mixture wich can cause detonation. The back sides of your intake valves will become caked with collegiated oil. (my valves and piston tops where)
This is a very serious problem, and combined with DOD activation, it is easy to burn thru oil rather quickly. Definitely not good..
Old 03-13-2011, 08:18 PM
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Originally Posted by 2005gxp
vaccuum vent. i dont have my tube on there anymore. no issues.
Maybe a turbo car is different, but when I ran both the clean and dirty side into the manifold under vacuum I saw a nasty buildup of condensation in my valve covers... not good.

Originally Posted by f3racer
i replaced the tube with a small filter.
I wouldn't recommend that... you are creating a vacuum leak. I screwed this up a while ago, because the PCV system is different on newer cars and I didn't realize it at first.

There is a clean side and dirty side to the system. At WOT, both will flow into the manifold. If you do a lot of high RPM stuff, like land speed or circle track racing, you'll actually want to put a catch can on BOTH sides!

At part throttle, air flows through the MAF (and is therefore metered) and into the clean side, through the crank case, and out the dirty side. This cycles the all of the nasty blow-by back into the combustion chamber and out of the exhaust. There is a lot of stuff you don't want in there, but iirc sulfur dioxide is the biggie. It's acidic, and will rot the engine out from the inside. The metered air that flows through the clean side mixes with the blow-by, but the blow-by isn't combustable so it doesn't matter from a fueling perspective.

So, you want to leave that tube hooked up between the MAF and the throttle, and the dirty side should always go directly into the manifold. Using breathers not only messes with emissions, but also shortens the life of your engine.
Old 03-13-2011, 10:41 PM
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Originally Posted by nmp0098
Maybe a turbo car is different, but when I ran both the clean and dirty side into the manifold under vacuum I saw a nasty buildup of condensation in my valve covers... not good.



I wouldn't recommend that... you are creating a vacuum leak. I screwed this up a while ago, because the PCV system is different on newer cars and I didn't realize it at first.

There is a clean side and dirty side to the system. At WOT, both will flow into the manifold. If you do a lot of high RPM stuff, like land speed or circle track racing, you'll actually want to put a catch can on BOTH sides!

At part throttle, air flows through the MAF (and is therefore metered) and into the clean side, through the crank case, and out the dirty side. This cycles the all of the nasty blow-by back into the combustion chamber and out of the exhaust. There is a lot of stuff you don't want in there, but iirc sulfur dioxide is the biggie. It's acidic, and will rot the engine out from the inside. The metered air that flows through the clean side mixes with the blow-by, but the blow-by isn't combustable so it doesn't matter from a fueling perspective.

So, you want to leave that tube hooked up between the MAF and the throttle, and the dirty side should always go directly into the manifold. Using breathers not only messes with emissions, but also shortens the life of your engine.
Great post/response as I was just thinking about all of this stuff today while driving around. (4.00 per gallon)

The clean side air should be left intact.




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