how to check a knock sensor

[Huw Powell]

> I was told once that a decent way to check a knock sensor is to hook up a
> timing light to the car and with the car running, tap (not too hard) on the
> engine/head with something (i.e. a wrench, etc.).  The way I understand it
> is that the light should indicate if the ignition is being retarded as
> compensation for the "knocking".  Whether or not this truly works, I don't
> know as I never bothered to learn how a knock sensor "reads" knocking.  I
> also don't know how this might be complicated by a dual KS engine - but I
> suppose you could disconnect one at a time to isolate the other one for
> testing.  P.S.:  If you try this, could you let me know if it works?

We did this once on some 4 cyl VW that had just had new engine
management installed.  It works like a charm.  Tapped right on the
sensor, gently, with a fairly small screwdriver.

-- 
Huw Powell

http://www.humanspeakers.com

http://www.humanthoughts.org