Cold Fouling/Carbon Fouling
WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
Cold fouling is sometimes referred to as carbon fouling. The deposits that cause cold fouling are basically carbon ( Figure ). A dry, black deposit on one or two plugs in a set may be caused by sticking valves or defective spark plug cables. Cold (carbon) fouling of the entire set of spark plugs may be caused by a clogged air cleaner element or repeated short operating times (short trips).