[Ford Man]

My '88 Escort has the old heat riser system where there's a duct that goes from the exhaust manifold to the breather (explained for you youngerns) and opens to let warm air into the breather during cold starts to help warm up the engine and help vaporize the fuel. I recently got the idea to block the door from the exhaust manifold to the breather in the open position all the time to act as a WAI. Since doing this I've been seeing considerablely better mileage. MPG since doing this have been 46.478, 41.976, 44.198, 44.2 and 42.853. Some of these mileages are in line with what I usually get during summer months when the weather is warm and have summer blend gas.