Knock sensors for 20v

[urq]

There is no question that you can see an output signal from a generally
functional knock sensor on an oscilloscope, but even that isn't going to
tell you for sure that it is functioning as the ECU is expecting it to.  It
is also true that rapping on the engine block can generate a signal the ECU
can interpret as knock ... in fact one of my favorite automotive
troubleshooting finds was a friend of mine who had a VW GTI that was down on
power ... I connected his report of a broken AC mount to the knock sensor
and got him back to full power ... but even that isn't going to be a sure
sign.

I'd say the best tool to use to tell you if the knock sensor is functioning
as intended is to check codes from the ECU.  On most newer cars (i.e. many
of the ones with knock sensors) the ECU will generate codes for excessive
knock as well as if it is not seeing the expected signal.  It might be good
to take the car out for a good flogging before checking the codes ... 

Steve Buchholz

-----Original Message-----

Does any one know for sure if this can be done?
How or what could you measure to see if timing retarded?  Does it 
automatically retard at the first sign of knock? Will it ever turn on a CEL?

I can check a knock sensor in my hand with an oscilliscope, BTDT.

----- Original Message ----- 

> Since a knock sensor is a microphone, could it be tested by gently 
> knocking
> on it with the handle of a screwdriver and see if the timing is retarded ?
>
> Louis-alain