Originally posted by qtiger
VTEC system requires a specific amount of oil pressure to operate. If you're low on oil you may not generate enough.
Back to the main question: Sounds like it may be a solenoid or filter problem. Those solenoids have a little filter on them that can get gunked.
Do you have an oil pressure gauge?
i agree, check the little filter by removing the solenoid, also check for obstruction and good conections on the solenoid and switch
~boom