[Gmecm] Getting rid of False Knock?

[Andrew Hopton]

As I think I read somewhere, the knock sensor is frequency sensitive.  The
range of frequencies being sensed for would also have to be of sufficient
amplitude to be ?counted?.  So you have 2 approaches open to you ? build
some kind of filter  (maybe low-pass, high-pass or band-pass) so that false
knocks are ignored (might be unfortunate that false knocks are same freq
range as real knocks) or control the amplitude of the signal (eg so only the
louder knocks are sensed)  This could also be a problem if the loudest
knocks are false ones.  Another idea is to use a second sensor placed close
to the source of the false knock (if you can determine that) and then use
its signal as negative feedback to cancel out/attenuate the false knocks
from the real signal (bit like a noise-cancelling microphone)

 

Cheers

 

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Jeff Stevens
Sent: Tuesday, 22 March 2005 7:39 AM
To: gmecm at diy-efi.org
Subject: RE: [Gmecm] Getting rid of False Knock?

 

I put a LOT of teflon tape on the sensor threads and tighten it just enough
to

prevent leaks.  Not even fully hand-tight.  I still get knock counts at
idle.

 

LJ

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Sixpakmak15 at aol.com
Sent: Monday, March 21, 2005 1:00 PM
To: gmecm at diy-efi.org
Subject: [Gmecm] Getting rid of False Knock?

Does anyone know how to fix false knock? i.e. different sensor, moving it,
ect... I'm trying to tune my LT1 but it's got a rediculous amount of knock
counts and it's really messing with my timming... Not sure what to do about
it... Thanks for any help...

Mike 


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