I know this is an outdated topic, but how much of an effect on gas mileage/performence does the PCV valve have?

i need to change mine - should i go for stock replacement, plastic mimic from car store, or the fancy aluminum ones???

thanks for the help

 

I have no idea how it affects performance, but in a thread started by Darkshear in February I can tell you the effect on the engine.

Check out this pic from his thread



As you can see, the cylinders nearest to the intake suck down the most crap from the PCV valve. Hence, the intake runners are caked with oily carbon (and people wonder why the throttle body needs to be cleaned/replaced on these cars). If you've never looked at the area around your intake tube right after the PCV valve connection, I'd advise you to do it. You'll be amazed by the stream of gunk coming from it.

The right thing to do is to replace it with an OEM part, but you can see what it does to your intake.

BTW - here's a link to his entire VERY INFORMATIVE thread (link).

 

alright thanks, very nice linked pics by the way...