the ks3 gain can be adjusted so there isnt a problem there - is the same possible on the vems? (i havent got mine yet so cant check )
can the stacking thing be checked? id try but ive no idea what im doing from what youre saying cliff it sounds feasible
Sure it can - stack them up and connect the 2 sensors to a scope - first run the engine up in a no knock condition (safe ignition) and check that there is a sensible base signal - nothing that looks like det. Then get the thing detting and check the signals - if they are the same, and you can see the det , you have a winner.
Anyone got an engine and scope we can try it on??
For info, when using a scope for looking at knock sensors, you will be able to tell the difference betwen base engine noise and det by the regularity. Base noise happens every cycle, so in term sof time its a regular pttern, whereas det is semi-random. We used an anaolgue scope with an infinately adjustable time base, and I then tweak that so that I end up with the signal just slowly scrolling past when the engine is running at a fixed speed. Its then very easy to see the normal noise pattern, and the det 'spikes' which appear additionally from time to time.