merf23

Does anyone know the specs on knock sensors; specifically what voltage output correlates with detonation?

Tim Burgess

There is no specific knock sensor voltage output that corresponds to a detonation threshold. The knock sensor is a "microphone" that "listens" to a specific frequency spectrum. The signal is most likely sent to a processor circuit that does a FFT (fast fourier transform), or frequency analysis, on the signal to determine if certain frequency spectrum components are present in the knock sensor signal at specific magnitudes. If a certain criteria are met, the presence of preignition or detonation are confirmed, and the spark control algorithm backs off the timng, probably using the "knock" measuring circuit in a feed back loop to incrementally back off the timing until the "knock" is no longer present.

Tim

merf23

Since my computer is no longer being used, I was hoping to be able to wire a warning light/LED to let me know if any inaudible detonation was occuring. Guess ill have to buy one of those $140 deals from Jegs
thanks