AFAIK, there isn't a "0" position for the ECU. It should be set to where idle speed/emissions are correct and there are neither cold nor hot starting or idling issues. It will change every time you adjust the MAP and/or the air speed screw (the large screw where the hose from the left valve cover leads to). It's like the MAP - there isn't really a position where you can say "This is default, anywhere from here is a setting not at default" or whatever (although you really can't stall the car out by changing the ECU screw, you can with the MAP if you go too far).