pinging?
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From: Dry Branch
People often confuse preignition and detonation. Preignition is the condition where the charge is ignited prematurely. "Prematurely," in this context means before the plug fires. As a result, preignition cannot be caused by too much timing advance. However, preignition means the charge is ignited before it should be, which is the same thing that happens when the timing is over-advanced.
Detonation is the condition where the fuel explodes rather than burning progressively.
Preignition is not audible until it causes detonation, but preignition can manifest itself directly, as when a car continues to "run on" after the ignition is switched off. Light "pinging," "spark knock," or "death rattle" are termes some use to describe light detonation (the detonation of only a small part of the charge), while heavy detonation is often called "knock."
Our cars have a knock sensor and software that "listens" for the sound of detonation and pulls timing when the detonation level becomes excessive. This will normally be long before there is enough detonation for a human to hear (and long before there is enough to worry about).
Detonation is the condition where the fuel explodes rather than burning progressively.
Preignition is not audible until it causes detonation, but preignition can manifest itself directly, as when a car continues to "run on" after the ignition is switched off. Light "pinging," "spark knock," or "death rattle" are termes some use to describe light detonation (the detonation of only a small part of the charge), while heavy detonation is often called "knock."
Our cars have a knock sensor and software that "listens" for the sound of detonation and pulls timing when the detonation level becomes excessive. This will normally be long before there is enough detonation for a human to hear (and long before there is enough to worry about).
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Joined: Jan 2006
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From: 17 ft below sea level.
With my "pre-detonation" I covered it all with one word.... 
(but it made no sense... sorry)
Good explanation RED-MX5
Question though: preignition could be caused by some carbon build-up (on a valve most likely?) that starts to "glow" like a spark plug right?
And then burns the fuel before the spark plug sparks, right?
And detonation, or "fuel explosion" is caused by fuel being compressed (and heated up because of that) beyond its flashpoint so its explodes on its own, whenever it reaches the flashpoint.
(almost like a diesel, but then not controlled), right?
And that exploding could start anywhere in the mixture, not like burning from the top of the combustion chamber downwards.
And from what I remeber detonation is most likey to occur under heavy load, being low revs and WOT.
Is that correct?
(but it made no sense... sorry)
Good explanation RED-MX5
Question though: preignition could be caused by some carbon build-up (on a valve most likely?) that starts to "glow" like a spark plug right?
And then burns the fuel before the spark plug sparks, right?
And detonation, or "fuel explosion" is caused by fuel being compressed (and heated up because of that) beyond its flashpoint so its explodes on its own, whenever it reaches the flashpoint.
(almost like a diesel, but then not controlled), right?
And that exploding could start anywhere in the mixture, not like burning from the top of the combustion chamber downwards.
And from what I remeber detonation is most likey to occur under heavy load, being low revs and WOT.
Is that correct?
Joined: Oct 2002
Posts: 22,661
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From: St-Redempteur,Qc.
Originally Posted by RED MX5,Jul 23 2006, 02:17 PM
Damn Emil, you really are over a hundred years old. 
Seriously,I tought we had a double points distributor,in there somewhere...
