OXY FEEDBACK TRIM (range of 60 to 140%)

Just like the fuel trims, this is also a closed loop value only this is the "short term" value and it determines the adjustments made to the "long term" fuel trims. As you drive along it will switch (cycle up and down) just like the O2 sensor voltage. It should be a nice, smooth and even switching rate, not jittery or jerly up and down. If it is switching from say 80% to 120% then you are right at 100% value, there's that stoichiometric word again. :-) If it's switching above 100% it's showing lean, and if it's switching below 100% you are running rich. Based on this info, under certain conditions the ECU will adjust the appropriate fuel trim until it sees the oxy trim switching closer to stoich.

Driving along with this value displayed is great for seeing how the car runs under normal driving conditions. I try to keep mine switching from around 100% low valleys to 140% high peaks. This will show it as a little lean on the fuel trims and it gives me the best drivability and good gas mileage.