way to check tha knock ?

[Kneale Brownson]

Aren't these sort of like a stretch bolt, in that once you torque the
fastener, you cannot reuse the sensor?  Thought I read that here some time
back.

At 02:59 PM 12/13/2004 -0800, Tony Lum wrote:

>The knock sensor is a piezo (crystal) microphone.  In other words 
>vibrations distort crystal element which then generates a voltage.  IMHO, 
>one way to check it is to use an oscilloscope (because piezo is high 
>impedance) bolt the sensor to a block of metal and then tap the block with 
>a hammer and observe if there's an output.  No BTDT, though and nobody's 
>actually done it.