[s-cars] Valve cover leak causing boost drop?

[Dace Voit]

Replace the check valve under the intake manifold. It's hidden in a reducer hose under a 'T' hose that connects to the under side of the IM just after the throttle body. While you're in there check the status of those little hoses. They Are a bit fragile with age and can tear easily. If that check valve is leaking it will allow the air to pressurize the crankcase and the valve cover.