My Jeep Cherokee 4.0 (1996) has some form of Positive Crankcase Ventilation valve which links to the intake manifold. Can these be removed and replaced with simple mini-K&N type filters?
My car runs LPG 99.9% of the time so needs minimal emissions controls.
I expect this is a PCV valve. As you say it draws a vacuum on the crank case and passes the fumes into the manifold to be burnt. Maintaining this vacuum helps prevent oil leaks (and some claim increases HP) so removing it and replacing with a filter may not be a good move.
