It just started doing this, its a 2010 f150 with a 5.4, When you mash on it once its hits 3000 rpm it starts and gets louder until your rpm drops down. It sounds like it coming from the passenger side somewhere almost like its not underthe hood at all! The noise is kind of like a sucking or scatchy sound, really hard to describe??? any help on this issue?

 

Take it in, - it's under warranty right ? Yea , take it in, let the techs have it. You can also go over the TSB's, to see if there's any info on the problem.