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Old 10-20-2013, 05:14 PM   #196
Firebird2xc
 
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Drives: car
Join Date: Jan 2013
Location: Las Vegas, NV
Posts: 94
Tech Question:

I bought a breather cap for my oil filler tube along with my catch can. I've heard guys say that the 'unmetered air will affect your fuel/air ratio' but that's dumb. How would air enter the fuel air mixture via the crank case unless it was causing severe piston ring blow by? It wouldn't.

As I understand PCV systems, the PCV valve should close when the engine isn't generating internal pressure via combustion. As the crank case would also be generating oil pressure, and thereby excess gas pressure in the fill tube.

I'm assuming the filler tube cap is a check valve?

It only lets vapor out when the engine isn't generating oil pressure? That the excess gaseous pressure being vented from the crankcase prevents pressure from being exerted on the piston rings when the cylinders aren't being regularly pressurized?

Anybody?
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