I bought a 4" standard airbox intake from PCMforless. It comes with a K&N breather filter for PCV. Should I use the breather filter or put a fitting in the pipe after the MAF for the PCV system.

Basically my question is should the PCV use metered air or not?

 

I just put the k&n on mine. It is not metered due to the fact of being after the MAF. In some cases the oil mist can gum up the throttle body over time. If it was critical, PCMforless would have installed a nipple on the intake tube. A lot of the big HP ls guys run catch cans from the pcv valve so no oil is introduced back into the intake.

 

Any unmetered air entering your engine can cause it to run lean. Are there guys running breathers? Yes. Are there a lot of guys that have way more knowledge of tuning using closed systems? yes. Also, having a closed system is better for the environment, you won't smell any fumes and no oil leaking everywhere like some have reported.

Catch cans are a good idea even for stock motors. Ingesting oil can lead to detonation, sludge build up, etc.

If you want to learn a lot about PCV system and catch cans check this thread out. Jump to and read posts #38-41. Sc2150 is full of info to the point your head will hurt and he's got some interesting pics too.

https://www.performancetrucks.net/fo...-500389/page4/