Originally Posted by dexx
The computer only adjusts the timing in response to knock. The design tolerances are for fuel, not what some monkey might do to their well engineered system. Changing anything in the exhaust means immediately the "correct" timing advance for any given RPM or load point has changed. Unfortunately, freer flowing exhaust means better exhaust evacuation from the cylinder, which means the optimal timing point is retarded compared to it's previous location. This means the first guess by the computer is much too advanced. What happens when you run too much timing? RIGHT.
You have to be a scientist and a computer engineer to understand how it really works, there is no explanation that will be satisfactory for any layman, but if you're curious as to how these things work: http://forums.openecu.org/
Ok. This has to qualify as THE DUMBEST STATEMENT
on the entire forum. The ECU is monitoring tens of sensors (from throttle input to air fuel ratio to exhaust gas temp to O2 in exhaust and on and on)and adjusting timing (which includes ignition, valves, etc.) many times per second. If you think the ECU waits until the knock sensor activates to start adjusting the timing you really need to go back to that site and re-read it.
Sadly, your comment with regards to having to be a scientist or engineer to understand the content on the site
let's me know you are neither. If I am somehow mistaken about that, then do your Alma Matter a favor and keep the name of the school to yourself.