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Message: <blockquote data-quote="PoManNox" data-source="post: 22447" data-attributes="member: 8300">I was curious on how the PCV system worked on the LYX 1.5 turbo and asked on another board I frequent.   A fella over there posted this:"You can't see the PCV that's used under vacuum, It's integral to the valve cover, cylinder head, & intake manifold. 3 in the diagram.Operation.....The crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting vapors to the atmosphere. Fresh air from the intake system is supplied to the crankcase and mixed with blow-by gases inside the crankcase. Blow-by gases rise to the top of the engine and are picked up into the oil separation chamber in the camshaft cover, where oil is separated from the gases. Blow-by gases are then passed to the intake manifold to be consumed by normal combustion, through a calibrated orifice inside of the camshaft cover.Fresh air is brought into the engine through the positive crankcase ventilation (PCV) valve (4) as long as the crankcase is under vacuum. The primary control is through the PCV orifice (3) which meters the flow into intake manifold, at a rate depending on manifold vacuum. The PCV orifice is an integral part of the camshaft cover. Under certain operating conditions, the system is designed to allow excessive amounts of blow by gases to flow through the <a href="https://my.alldata.com/repair/#/vehicle/55614/component/381/filter/noFilter" target="_blank">PCV valve</a>s (1 or 2) depending on if the engine is in boost mode or excessive crankcase pressure is detected and then routed into the intake system to be consumed by normal combustion.Turbo Applications:During normal operating conditions the PCV gases are routed using PCV valve (3) and the internal passage within the camshaft cover. When the Turbo is active, check valve (3) is closed and check valve (1) opens and PCV gases are routed back to the turbocharger to be consumed by normal combustion. If the engine sees excessive positive crankcase pressure check valve (2) opens and the pressure is routed to the air inlet to be reintroduced into the engine.Non-Turbo Applications:During normal operating conditions the PCV gases are routed using check valve (3) and the internal passage within the camshaft cover. If the engine sees excessive positive crankcase pressure check valve (2) opens and the pressure is routed to the air inlet. Also for non-turbo applications check valve (1) does not exist.In any application check valve (2) is only used if the engine sees excessive crankcase pressure."[ATTACH=full]2414[/ATTACH]</blockquote>

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