knock sensor functionality - '85 L98
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Pro
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From: North Bay Ontario
knock sensor functionality - '85 L98
With a proper working knock sensor, is it possible or *normal* to hear the onset of pinging (i.e. - the first "ping") before the knock sensor senses it, communicates with the ECM and timing is adjusted. If yes, to the first part, does the timing get readjusted as soon as the pinging stops.
Race Director
Joined: Jun 1999
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From: Merritt Ils Fl
Yes, you can hear a ping, or at least I can. EST pulls timing until pinging stops then adds it back as long as there no ping. If I recall correctly the pull and add back is in 2 degree increments.
I best add this is what I recall reading about my 85. Do not know if it applies to other years since 85 was a stand alone year ECM wise.
I best add this is what I recall reading about my 85. Do not know if it applies to other years since 85 was a stand alone year ECM wise.
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From: North Bay Ontario
This is interesting, because I've been driving for about 40 years, I can say that I *remember* what pinging sounds like - but of course in more recent years with fuel injection and EGMs the sound of pinging is basically a thing of the past. I haven't heard an engine ping in years!
Since getting my '85 about 5 years ago, I've often puzzled over this odd noise (I kept thinking it was a slight "backfire" through the throttle body) that I hear sometimes when I suddenly put the horses into it. I'll bet now that it's the first sound of a ping.
I put a new timing set in the car last year, and set the timing to specs, but have always run just reg 89 octane fuel. Perhaps I'll try a tank of higher octane and see if that makes a difference.
Since getting my '85 about 5 years ago, I've often puzzled over this odd noise (I kept thinking it was a slight "backfire" through the throttle body) that I hear sometimes when I suddenly put the horses into it. I'll bet now that it's the first sound of a ping.
I put a new timing set in the car last year, and set the timing to specs, but have always run just reg 89 octane fuel. Perhaps I'll try a tank of higher octane and see if that makes a difference.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
With a proper working knock sensor, is it possible or *normal* to hear the onset of pinging (i.e. - the first "ping") before the knock sensor senses it, communicates with the ECM and timing is adjusted. If yes, to the first part, does the timing get readjusted as soon as the pinging stops.
Newer engines are quieter mechanically, which allows a more sensitive ESC calibration. Also, ECM software available in newer vehicles is more sophisticated and can identify at what piston/crankshaft position the noise occured at, and help to discriminate between random noise and crank angle positional knock.
Team Owner
Joined: Jul 2004
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From: Hartford WI
With a proper working knock sensor, is it possible or *normal* to hear the onset of pinging (i.e. - the first "ping") before the knock sensor senses it, communicates with the ECM and timing is adjusted. If yes, to the first part, does the timing get readjusted as soon as the pinging stops.
I would assume that if you can hear it, that means it is outside of the ECM range of adjustment.
