PCV leak
It's perfectly normal for the engine to idle down when you seal the PCV valve completely off. Since the PCV system is not closed, it is more or less a controlled vacuum leak. That's how it operates. See attached.
It's perfectly normal for the engine to idle down when you seal the PCV valve completely off. Since the PCV system is not closed, it is more or less a controlled vacuum leak. That's how it operates. See attached.
