A common mis-conception is that higher octane means a slower burn. That's not the case. Octane in gasoline is the fuel resistance to detonation.
Also often mis-understood is pre-ignition vs detonation.
I won't get into brands because truth is none of us know for sure what is what.
I do have good experience with Amaco 93, shell 93, an sunoco 94.
For this thread "detonation" is the issue.....
What happens in all cases is that the fuel is conducting heat from the metal parts of the engine, the air is highly compressed (also very hot), and so this air/fuel mix is right on the verge of exploding. The sprak plug sparks and sets off the burn. At least this is whats supposed to be happening.
Well in this threads issue of cheap gas and "pinging", the fuels *quality* and/or *octane* is just low enough that the air/fuel charge starts to burn inconsistantly for the given load. It could be the octane.. it could be the lack of certian additives.. or a combination of the two.
The air/fuel charge litterally starts to burn in multiple areas all at once. That causes the flame fronts to crash into each other, reach the piston face at differing times, and to cause random shock waves that bounce all over the combustion chamber within those few miliseconds when the piston is just about to reach the top of it's stroke. If bad enough the pcm CAN'T retard spark enough and you'll hear an audible "knock". (the stock ford tune on my 2006 has a 7 degree limit when retarding)
A better quality fuel (like shell V-power) will have the ability to resist this spontanious combustion in multiple areas. It will only be ignited when the spark plug sparks. Thus the flame front is a single one and hits the piston face in the way that ford designed it to happen.
I know it's temping to just put the cheapest gas in. But there is no way to get around this unless you either lower the load, back off the timing, or increase the PCMs ability to retard timing. Or... just buy quality gasoline to begin with.
Also, if by chance the fuel is not atomized well (dirty injectors and/or carbon on the intake valve) it can also contribute to detonation.