Re: Testing Knock Sensors

[Huw Powell <audi@mediaone.net>]

> This method has been mentioned before, although I haven't used it or
> advocate it myself.
> 
> Take a long bar that can reach the block around cylinder #1 on the sensor
> side. Should be made from steel. Tap the free end lightly with a hammer
> and see the voltmeter connected to the plug fluctuate. I'm sorry that I
> don't have specifics.

you also should be able to watch the flywheel with a timing light, as
your talented assistant taps the block (or the sensor - but with
something light like a thin screwdriver - very lightly!), you will see
the timing get retarded as the ECU "hears" the knocks you are making and
takes corrective measures.

This of course also tests the whole system all at once, if something
isn't working you won't know what it is.

-- 
Huw Powell

http://www.humanspeakers.com/audi/

82 Audi Coupe; 84 4kq; 85 Coupe GT; 73 F250

http://people.ne.mediaone.net/audi/thoughts.htm