Quick question on the 4afe...

[fistofmeat]

there are two rubber tubes going from the top of the head cover of the 4afe to the intake manifold at different spots, one small and one a little bigger. are they sucking air from the manifold, or blowing air into it?

[Flashmn]

PCV system, the one on the pax side brings replacement air inside the head, so that theres no vacuum. the drivers side is the pcv valve.

[fistofmeat]

thanks flashmn, out of curiosity, why does it need to pull in air into the head? what happens if there's a vacuum?

[fistofmeat]

ok you don't have to answer my last post. i researched the pcv system and now im intrigued... a good oil catch can (good means GReddy or Megan) is not too expensive, an ebay crap goes as low as around $30 shipped. the question is is it worth it? is there enough oil being expelled into the intake manifold to make it a worthwhile modification? i know it's possible to have it route to the oil pan, but is it difficult to do? would i be better off just emptying the oil can and recycling the oil with the oil change? since it is technically dirty oil, it shouldn't go back into the pan right? does any substantial amout of oil go into the can through the IM return valve? would i be replacing it every couple of days? wouldn't that be bad if i were? does the oil burn easily enough in the cylinder to not make a difference, or will there be a noticible change in the car's behavior?

[Flashmn]

There wont be any noticeable difference. Without the PCV system your oil will degrade faster as basically the gasses in the engine (which go out the engine via the PCV system) are blowby from cylinders and thus basically they're exhaust gasses. Exhaust gasses contain contaminants.

You should only use a catch can if you cant use the normal PCV system or just let it be an atmospheric PCV system.

I'd say leave the stock one intact and rather get rid of the EGR system if you have such, thats alot worse in contaminating the intake manifold with crap.

[ganda1f]

Not sure if I got the idea behind EGR correctly, but isn't there a chance that getting rid of it could cause at least two problems? One, higher combustion temperatures, but perhaps ECU is able to prevent pinging somehow? Two, trouble passing emission checks?

[Flashmn]

1) is not really applicable, EGR on a corolla doesnt work past 3000rpm (as far as I know). Besides getting the 4A-FE head to knock is really hard.
2) Yes.. .but there are ways to get rid of it, so that the checker doesnt know