I was learning about PCV valve, when one of the online resources pointed out that the PCV valve will be closed during high engine load to prevent the lean-mixture (blow-by) in the crank case from entering the combustion chamber, as a lean mixture is not desirable during high engine load. But my basic automobile engineering textbook (local author) points out that during higher engine load, the blow-by increases and causes the crank case pressure to rise thereby increasing the opening of the PCV valve and letting more blow-by enter the combustion chamber.

Now I'm confused wether the valve actually closes or opens during high engine load.

  • $\begingroup$ If the PCV valve is electronically controlled in the first example I could see both these being true. If you want to increase performance by avoiding a lean mix, you could keep the PCV closed or at a reduced opening when your crankcase pressure is high. But for most PCVs (the few I've come across), they're mechanically driven so they only open at high pressure. $\endgroup$
    – jko
    Jan 6, 2021 at 15:45


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