Its been makeing this strange hissing sound only at idle when the engine is warm. Then if i give it a few hard revs it clears and stops for a little. It sounds like its comeing from the solenoid valve. Is it cloging up and needs to be replaced? Any help will be appreciateed.

 

Your Vapor canister you pointed out the other day would not make a noise. It runs around 1psi or less. Also if it was leaking it would throw a CEL P0457. Check all vacuum lines