knock sensor signal

[Tristan 0]

What kind of signal makes the knock sensor? Can it be measured? I want to advance the timing and need something to see the detonation level.

[dr_mat 0]

I think you want a stethoscope ..

 

The knock sensor is just a microphone, "listening" for knock. You can listen too.

[Tristan 0]

Yes I know that but it has to send some kind of signal to the ECU... :) can't use a stethoscope at 100 km/h :)

[dr_mat 0]

Well yeah, it's a microphone, so it sends an *audio* signal back, which the ECU then listens to!

I wouldn't know exactly what knocking looks like on an oscilloscope, but that's what you're looking for...

I have no idea how clear it will be, because let's face it you're going to get all sorts of other noises too from the rest of the engine, so you'll need a pretty smart neural net to pick out the knock from the other clanks and whistles.

[Tristan 0]

I'll try using an osciloscope.... think that will be best.

Thanks dr_mat :)

[Roger Blassberg 0]

I expect that it is a piezzo-electric device, that is it turns a physical shock (detonation, pinking, pre-ignition, call it what you like) into an an electrical impulse which is read by the ECU and causes the ignition timing to be stepped back. They are rather sensitive to the through-bolt tension, needs to be done up to the exact specified torque; too tight and it's damaged, too loose and it doesn't pick up the shock properly.

 

Best wishes

 

RB

[Yandards 0]

The knock sensor listens at a frequency of 12khz if that is any use.