Does anyone have a suggestion a simple method how I can find out when the factory controller decides it detected knock?
I assume it could be done by monitoring sudden changes in ignition timing, but I think it would be difficult to set up a scope trig condition for that.
What I want is to monitor the knock microphone using an oscilloscope and have it trig on knock detection. Then the scope can do an FFT analysis of the stored trace. Or save it on a USBstick for later analysis. But if it is not known that the sample is taken during a knock condition, it will not be of much help.
There's also a limitation on the depth of a trace that means it can either take a short duration high bandwidth trace, or a long duration low bandwidth trace. So logging a run with one channel on the microphone, one on the ignition and a the remaining 2 on the crank + cam sensors for later finding out where the ignition retard is will be a shot in the dark.