venting the crankcase questions

[Brian Link]

Gang,

A few questions that I need some help on.
A recently performed output test with my prodiag, I noticed that I could
not hear the carbon canister valve clicking open/close.  So I wonder has
anyone replaced the valve, what symptoms would result in a faulty
canister valve?

Also, when the system is working correctly, when does the valve cycle
open?  Does the system tend to vent crankcase fumes into the intake
under wot?  Or at idle and part throttle?

Thanks

Brian Link