A malfunction of the PCV system is likely to cause all of these problems EXCEPT:

A malfunction of the Positive Crankcase Ventilation (PCV) system can lead to various issues in an engine's operation and performance. One of the key functions of the PCV system is to route blow-by gases—which are gases that escape from the combustion chamber during the combustion process—back into the intake manifold for re-combustion. When the PCV system fails, it can cause a buildup of pressure in the crankcase, leading to several potential engine problems.

Excessive blowby is not likely to be a direct consequence of a faulty PCV system. Instead, the condition of excessive blowby is typically a result of worn piston rings or cylinder walls, allowing more combustion gases to escape into the crankcase than what the PCV system could normally handle. Therefore, while a malfunctioning PCV system can exacerbate existing conditions, it does not directly cause excessive blowby on its own.

On the other hand, an illuminated Malfunction Indicator Lamp (MIL) can occur because of increased pressure or performance issues resulting from a faulty PCV system. Additionally, a malfunctioning PCV system can lead to a rough or unstable idle as the air-fuel mixture is affected by the incorrect crankcase ventilation. Further, an improperly functioning