is there a way to adjust the A/F ratio in the Gs3 without a A/F controller? like if i had a A/F gauge and saw it was running too rich or lean...would i not be able to do anything about it without a controller?
Thanks

 

^ yep cant do anything. need the controller. its all done by the ECU and the controller intercepts the signal allowing you to manipulate what the ecu does for fuelling

 

There is no reason why the fuel trim will change, unless there is something wrong with the car. Also, how will you be reading you A/F ratio? The short band is not an acurate way to read A/F ratios anyways.