I've had this thing in my car since day 1 of owning the car, and to be honest I never thought about it. The Apexi goes off of the o2 voltage, but they use a generic table of voltages- is there a correct one for FC's. They use this to determine A/F and thus the idle time, but is it correct? I did a search and check the service manuals but I don't think it's been brought up or concerns anybody but me.