I have a whining noise underneath the hood of my minivan. The noise can only be heard when accelerating and stops when I let off the gas pedal. Please advise!:o

Sounds like it's supercharged ! Anymore vehicle information you can give us? Make, model, year, engine??

Using a mechanics stethoscope, or large handle screwdriver, should help you isolate the noise. Possibilities are serpentine belt, tensioner pulley, alternator, power steering pump, or water pump. Have someone increase engine speed, while you open the hood and listen.

It may be a bad timing belt. After 58k miles, I had the similar sound with my Dodge Caravan. My dealer diagnosed as bad timing belt. I need to have it done every 60k or so anyway so I did it. Afterwards, the noise went away.