I have a new-to-me 2005 Accord 4 cylinder and have a question about a humming or whistling sound coming from the engine area. It only happens under acceleration at hwy speeds. It sounds like a possible intake leak or something but I can find nothing obvious. It only happens with my foot on the throttle. As soon as I let off it quits and then picks right back up when I'm back into it again. Any ideas?