Well if you went from 2 to 1 then you'll need to adjust the screw. OBD2 doesn't have an adjustment screw, and the isv is built into the OBD2 t/b. The isv controls the idle (to keep it smooth and regular) via by-passing the t/bt, but the t/b needs to be set too as when the engine is up to temp, the isv is no longer used-mostly used when the engine is cold (when it requires more air/fuel til warm).