"When the EGR fails to open, combustion temperatures cannot be limited, causing higher cylinder temperatures and an increase in NOx emissions. Engine ping or knock may occur, especially when the engine is under load."

This is interesting to me as well, if the EGR sticks in the open position, Cyl head temp rises. If ping or knock occurs then I would presume that the knock sensor would retard the timing, since the timing is initially retarded for emissions control the very least occurance would be a corresponding decrease in the complete ignition of the fuel/air mixture. ( Poor Gas mileage- less power).

I am not sure that the rear seal in this particular instance is an issue when the Isuzu engine PVC fails closed. The seal most certainly has failed in the past (other engines) whenever crankcase pressure has been excessive but I am unaware of crankcase seal failures in Isuzu engines.

It is an interesting discussion but unless Isuzu provides us with the failure analysis data (Highly unlikely) our theroms right or wrong remain unproven.

As for my VX, I think best to apply the aforementioned semi rigid prevention methods I alluded to earlier.