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      02-24-2011, 11:07 PM   #103
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If combustion is stable, there would be no abnormal noise for the sensors to pick up - -the noise would be normal combustion noise by definition. It is very unlikely there is a harmless, partially degenerated wavefront, that happens to create audible vibration, without any potential for harm.

I do believe that knock varies in intensity and severity, influenced by how far off the timing was, the load, temperatures, cylinder pressures, at which it occurs, etc. The less accurate the tune is at getting timing right, in light of all the factors, the more potential for knock events, in both severity and number. Catastrophic loss may be rare, but heightened wear and tear is almost certain.

I come from other engineering areas, and have no tuning background, but this seems obvious to me. Yes, I inferred it from what I've read here, but also did my own thinking and reading...

Originally Posted by View Post
The DME reaction to knock sensor feedback is progressive. Normally it operates within a range than reduces timing in small amounts of say 1/4 degree. If knock sensor noise is above that range it overreacts with 3 degrees. This is when you know it's having a harder time honing in on the right curve which means combustion is becoming less stable. If it continues you get another 3 degrees. Finally if there is still no reduction in knock sensor noise after the two 3 degree drops it assumes you are experiencing preignition or something bad is happening and goes to limp mode / triggers ignition glow codes. The whole time it is learning long and short term trims by RPM, load, gear, etc.