Originally Posted by OperationAlfa
Is it a dump valve?
No, I don't know how this Ecotek valve works but its not a dump valve. A dump valve is only for turbocharged petrols, when you take your foot off the throttle the throttle butterfly closes and the turbo starts spooling down but it is still sucking in air, which builds up outside the inlet manifold - the dump valve vents this build-up of air in a loud hiss.