[s-cars] Knock sensor failure?

[Joseph Pizzimenti]

Another variable in this equation is knock sensor
tolerances as far as what it interprets as knock and
what is simply engine noise.  As some of us on list
who have had aftermarket exhaust clearance issues can
testify to, excessive engine noise (like an exhaust
hammering away at a subframe or heat shield) can be
interpreted as engine knock and timing/boost may be
dialed back.

I was using an Apexi SAFC-II on my ricebox until about
a week ago and it wires into the knock sensor lead
going to the ECU.  Although the car was not knocking,
some engine noise was showing up, although timing did
not get pulled back until the knock count reached 200
or so.

As always, YMMV, blah, blah, blah.

Pizzo

--- MLP <mlped at qwest.net> wrote:
> As I recall, in the SAAB APC conversion / adaptation
> to other vehicles
> posts there is some information about the difficulty
> one can experience
> in trying to adapt the system, and the sensors to
> another vehicle.  One
> check was to be sure the sensor is properly secured
> to the block.  By
> properly secured as I recall, in addition to
> location, the sensors could
> be somewhat finicky about being squeezed ~ not too
> loose, not too tight.
> 
> While I don't recall any Audi lister ever posting
> "My sensors got
> loose...." in the Audi spirit of "My plugs keep
> moving, should I seize
> or anti seize etc....,"  I guess it couldn't hurt to
> check them.  OTOH,
> my guess would be this might be one part of the Audi
> system that doesn't
> "fail safe" (but I really don't about know this)
> i.e., if one or more
> knock sensors stopped working, wouldn't you get no
> signal at all,
> therefore no knock sensor protection, or do the
> sensors by default put
> out a signal which, if absent or "interrupted"
> begins a progressive
> timing retard, go safe mode?  
> 
> Some one (Rod H.) on the Krummer list questioned the
> value of a knock
> signal LED on the dash.  I suppose this would be a
> case where that could
> prove helpful.  If you were getting regular knock
> sensor activation LED
> activity while under little or no boost.....?  Last,
> does the VAG store
> knock sensor interrupt codes?  Would something like
> Shadetree Software's
> Palm OS allow running & monitoring the older system
> in real time to
> watch for KS activity? 
> 
> mike
> 
> >-----Original Message-----
> >From: s-car-list On Behalf Of Robert Myers
> 
> >Hi Y'all,
> >
> >I've been sitting here thinking...  (Miracles do
> sometimes happen.)
> >
> >I'm sure that knock sensors have failed from time
> to time but I would 
> >expect that the normal failure mode would be that
> it simply 
> >stop putting 
> >out a signal.  However, has anyone experienced a
> knock sensor 
> >failure in 
> >which the knock sensor becomes overly sensitive and
> reports 
> >knocking to the 
> >ECU when none is actually happening?  Is there any
> direct way 
> >to determine 
> >if this might be the case or would it be just a
> "replace and 
> >try" procedure.
> >
> >_____
> >
> >When Clinton lied no one died.
> >
> >Bob
> >*****
> >  Robert L. Myers  304-574-2372
> >  Rt. 4, Box 57, Fayetteville, WV 25840 USA  WV tag
> Q SHIP
> >  '95 urS6 Cashmere Grey - der Wunderwagen   ICQ
> 22170244
> >  http://www.cob-net.org/church/pvcob.htm
> >***** 
> >
> 
> 
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com
> http://www.audifans.com/mailman/listinfo/s-car-list


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