My AF number is 5 at idle and it maxes out at 255. It is a stock rebuilt unit and I'm aware that a lot of these are not calibrated correctly to begin with. My question is can a MAF sensor be out of calibration even though the numbers on my Scanmaster are telling me otherwise? Meaning, are there other variables that is output by the MAF sensor that cannot be monitored using just a Scanmaster? How about the ability for the MAF sensor to react to abrupt changes in flow that our cars produce?