Do our cars have oxygen sensors? I have seen them in a few catologs for the 320i. My car is 320i converted to 323i and seems to be running rich, could this be the oxygen sensor(if it has one) or is it that my fuel distribution pump needs adjustments? Vaccum leaks cause the car to run lean not rich right??? Tomorrow i'll try to get under there and look for one, BTW i'm running a header. Please help, thank you.