one_fast_300zx

ok i did a tune up on the Z, plugs and wires, cap and rotor and coil. but i noticed something on both the old and new cap. there is a plastic cover that comes off and has what looks like a vacuum line under it. its on the side of the cap where the coil wires plugs in. im just curious what it is? is there suppossed to be something hooked to it like for an option i dont have on my car? if anyone knows let me know. thanks.

PooFlinginMonke

It's a vent.