Testing Knock sensors

[R33E8]

Hi, I would like to test my knock sensor. I've read that they are piezoelectric devices and I happen to have a research project that deals with piezoelectric materials. I was wondering if I could use an impedance analyzer to determine whether or not my knock sensor is good or bad. If I do test it, is there anything I should look for? Would the capacitance be very low (broken ceramic material) or the loss factor be high (a short circuit)? The impedance analyzer I have access to is an Agilent 4294A. Thanks.

 

[patprimmer]

If you have any way to manually overide ignition advance you could keep advancing until you get knock and see if there is an output signal from the sensor, or you could use low then high octane fuel then test ignition timing for a difference.

Regards
Pat
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[R33E8]

Thanks, but my engine is apart right now so testing it like that is not possible.. The knock sensor is hard to change when the engine is assembled so I would like to test the knock sensor externally. I think I'll just buy a new knock sensor and find the differences...

 

[thruthefence]

http://www.eng-tips.com/viewthread.cfm?qid=54276

1st item on a google search, "knock sensor voltage output"

 

[patprimmer]

Incredible.

What google can do if only one bothers to use it.

Regards
Pat
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[SaBMWtech]

Use a hammer and a screw driver tap on the side of a block with an occillosope attach to both leads of the sensor if u get ac voltage ur good if u get none that its bad...