NOISE AT START UP
wHEN I START MY 2010 COBALT THERE IS A LOUD SHOOWSH NOISE AS
IT STARTS . AS THOUGH AIR WAS BEING PUSHED THRU A HOLE .
ONCE STARTED IT RUNS FINE. SOUND IS GETTING LOUDER
Maybe an exhaust leak of some sort? Cracked manifolds are common on some models and the crack might close up as the manifold heats up. Just a thought.