it's been really cold here in central ohio lately, anywhere from -20F to 20F. I've been hearing a noise from under my hood but i can't put my finger on it. the noise is intermittent and sounds like air sucking really hard. rpm's don't really effect the noise but the amount of throttle does. when accelerating there is no noise, but if i let off the accelerator it begins to suck air. as soon as i hit the throttle again it stops once. i can't recreate the noise when i'm in park so i believe there has to be back pressure for it to happen.