Under the right conditions, temp and humidity, running without preheated air entering the intake tract can cause carb/throttle body ice build up. This may not be a common problem with Deloreans but has happened to me on other automobiles and is entirely possible on the D. The engineers knew this and although the Delorean doesn't have the restrictive venturi of a conventional carb, it's still capable of icing up. "dmc6960" <ultra@xxxx> wrote: >I must disagree with you on this John. You say the air valve is to >keep water in the fuel system from freezing?