How can you tell if the tensioner is bad? I have a Vortech S trim and if i grab the belt over by the altenator and yank on the belt, i can easily pull some slack and watch the tensioner move. I would assume that having a really really tight belt is definately needed on a blown car and i shouldnt be able to move the tensioner by hand by just yanking on the belt. I wonder if this is the cause of why sometimes my car has full boost/ max power and other times, no boost/no power.