Air breather?

[Franko]

Well the whole reasoning behind the pcv system is this, whenever the car is running a certian amount of the combustion gasses get past your piston rings and make it down into your crankcase. Even with a very healthy engine this happens. These gasses still have fuel vapour in them and are still combustable, so they ran a line from the valve cover (valve cover.. crankcase.. its all connected) to the intake manifold. Under normal driving the intake manifold is under a vacum so what happens is it sucks out these gasses that didnt get burned the first time and gives them a go at it again. Then our old friend the o2 sensor can take a tiny smack of fuel away from the injectors (since the air is now slightly rich) and thus make the engine as efficent as possible, burning all the fuel.

The purpose of the other hose that dosent go to the intake manifold is so your intake manifold dosent put your crankcase under vacum. Thats just not nessicary so they run a line from a point AFTER the airflow meter so it takes in metered air and not just atmosphereic air. It also serves as another point for richer gasses to enter the engine when you are at wide open throttle since there is no vacum present in the intake manifold at that time. So the crankcase will be slightly pressureized from the blow by and it will still get burned in the engine by going through the throttle body.

The PCV valve serves a purpose too, If a situation ever occured where there was an explosion in your intake manifold the one-way pcv valve would not let the flame get inside your crankcase which would make an even bigger bang and you dont want that.

That is all fine and dandy but there is a flaw. During this process of recirculating the gasses back into the intake, its not only unburnt gas that gets sucked in.. its also oil and oil vapor. Yes the engineers have made several baffels in the valve cover to try and prevent this but it still happens anyway. When oil vapour gets into your engine it reduces the octane rating of your fuel and can cause detonation. So what many turbo people do is run hoses from both breathers to a catch can, then they put a breather on the can itself. Since this is illegal in ontario your only option then is to run the hose that would normally be in the intake stream and connect it to an area BEFORE the turbo but AFTER the airflow meter. If it was connected after the turbo then your crankcase would be pressureized by your turbo and that just aint good.. Seals blown and just general badness.

Ariesdude is right about the lean condition, removing the oil cap could cause a massive amount of unmetered air to enter the combustion chamber and choke the car. Having a breather would most likely cause a higher idle but not shut the car off due to the fact that the leak isnt big enough to cause a problem and that the engine is still sucking slighty rich air from the crankcase.

Remember, that breather is only sucking in air under normal driving conditions but once full throttle or a boosted condition is reached the pcv valve closes and the blow by gasses have nowhere else to go but out that vent and into our hearts... I mean into the atmosphere.

[ryan_Fuerte]

Having them breath to atmosphere is illegal in Ontario

Yah its something crazy like 500 dollaar fine