I think you want the white wire, look in a helms manual at the wiring diagrams.
way to put the cart infront of the horse. those af guages do work well as long as they are behind a wideband. the stock o2 sensor voltage threshold is too skinny so those sensors are only give a consistent reading at WOT.autometer air/fuel gauge is nothing but a light show. Won't actually tell you anything about how your car is running. Get a wideband and call it a day.