what can i do to check and make sure my vtec isnt going bad it doesnt sound right when it kicks in?

 

What engine do you have? or better yet what car model and year

 

94 honda civic ex it has the d16z6 sohc vtec.... when it kicks in it sounds like to pieces of metal scratchin together when im not in vtec it sounds great but when it kicks in it sounds horrible and there is a smell of like gas or some sort after vtec cuts off