Hmmmm, never heard this one. Was checking my A/C charge the other night with the engine idling, and whenever the compressor kicked off, there was a rattle from the PCV. Confirmed with the mechanics stethescope (ala screwdriver). It is a Fram. Must be busted somehow, like the plunger can't seal flat in there so it's just rattling around. My idle has been a bit rough as of late. Guess I'll try a dealer valve and see if it works.