RE: Testing Knock Sensors

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

Say what?  The test that was proposed as I read it was to artificially
create knock and then to observe the ECU changing the timing via a timing
light ... Orin's response based on his considerable expertise with the
internals of the code was that the ECU code ignores the knock sensor signal
unless the manifold is at 0.7 bar or above ... not too likely with the
engine unloaded.  Noone has said anything about whether or not the knock
sensor will still function or malfunction, just that the test that was
proposed was not likely to produce the desired result.  AAMOF based on what
Orin says people who run this test would likely decide that their knock
sensor is bad ... even when it might very well be good.  

BTW, thanks for the insight on the ECU code Orin!  Based on what you wrote
it made it clear to me why the Check Engine light behaves as it does when
there is a problem with the knock sensor ...

Steve Buchholz
San Jose, CA (USA)

> -----Original Message-----
> 
> That's when the ecu turns the regulation system on. That 
> doesn't mean that
> the piezoelectric crystal in the sensor isn't conducting. On 
> the contrary,
> it still is. An o2 sensor will still function even when the 
> system is in
> open loop.
> 
> 
> > > 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.
> > 
> > Probably won't work.  The ECU knock code only takes effect
> > over 0.7 bar manifold pressure.
> > 
> > Orin.
> > 
>