I believe he was referring to getting a knock signal per cylinder that can be used as an alternative better suited for filtering out false knock or noise from a built engine. The stock knock sensors are fine to a point but over a certain noise threshold they are inaccurate. Im not sure if it is an amplitude limit with the sensor or A/D that could be throwing the filtering off. Ive seen someone selling an upgraded knock sensor that can deal with this but I haven't had experience with it. Ive used the pot method but without checking the signal or knowing how the dme is filtering the signal, i am unsure .
