20v BT running rich

[RoninMax]

Are you using the stock ECU? If it is, that is normal. First, most of the time the engine is running rich on idle. Since the stock ECU only can read the narrow band reading (14.2 to 14.9 A/R). Once you are using the wide band O2. Your O2 can read from 11 A/R to 18 A/R. right?

But the stock ECU only can read 14.2 to 14.9 A/R. once it is not 14.2 to 14.9, The stock ECU will start putting more fuel (save mode) to save the motor (to rich will not blow the motor). Also, in idle, the ECU is already puting more fuel on idle (since it need to put more fuel to get the right A/R - Less Air density need more fuel to get the right mixture). That is the reason why you can is running rich on idle.