ATI & Check Valve
When your intake manifold sees positive pressure the valve closes so air can't get back into the PCV system. If it did the crankcase, which is directly linked to the PCV system, would become pressurised.
John <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
I thought the PCV system had 1 connection at the Throttle Body and another at the back of the valve cover? I need to draw this out and stick my head in the engine bay..
Take a look at the PCV system and you'll get it. The intake manifold has a port just behind the TB. The motor pulls the Crankcase gases thru this port and into the motor when not under boost. When the intake manifold sees boost the pressure tries to go out of this port on the intake manifold and fill the crankcase. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> Thats what the check vavle is for. It allows normal operation of the PCV port while not under boost and seals the PCV system from letting air into the crankcase under boost.
Good luck. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
John


