[Mgs] Knock and timing, was Overdrive Numbers

[Paul Hunt]

In that case it is a safety or emissions feature to *retard* timing from a 
planned map, i.e. the performance is unchanged between different octane 
fuels - as long as pinking doesn't occur.  The ones that gain benefit from 
higher octane fuels do *advance* the ignition over and above a planned map 
in small steps until pinking is encountered, than back it off more rapidly, 
continually.  See this Mazda RX for example 
http://www.shyauto.com/Downloads/RX0711.pdf.

----- Original Message ----- 
> And just because you have knock sensing doesn't mean that the car will
> automatically advance until it hears knock. It will more likely only 
> advance  until
> a preset (by the ECM) limit even if further advance over that would have
> produced more power.