pcv valve
 

what is the purpose of replacing the pcv valve?

Please don't post in the FAQ section, that area is reserved for commonly asked questions.

On most vehicles, the PCV valve allows crankcase vapors and moisture to be sucked into the intake manifold and burned during the normal combustion cycle. I won't go into much detail, but a quick Google search brought this website.

Keep in mind that 7M equipped vehicles do not use a traditional PCV valve

The valve in systems which use them are nothing more than a check valve... and the GTE has one built into the upper intake plenum where the PCV pipe connects. It is worth inspecting and cleaning from time to time (don't want the crankcase filling with pressurized air, you'll loose your seals)... but I admit I've never pulled one out. The other port see full time vacuum, but it's quite weak.