The PCV valve on a 1992 Chevy Lumina 3.1L V6 is located on the
valve cover. It's usually a small, plastic or metal valve with a hose connected to it. Precisely where on the valve cover will vary slightly depending on the exact engine configuration, but it's generally near the
rear (firewall side) of the valve cover.
You'll likely see a hose running from the valve cover to the intake manifold; the PCV valve is usually at or near the point where that hose connects to the valve cover. You'll need to visually inspect the valve cover and its associated hoses to locate it definitively.
