So my 02 has 116,000 miles, Im running a superchip programmer set to the towing performance setting, It will detonate or pre ignite when at WOT, from around 3500 rpm to around 4500 rpm. I have been running the chip since it was new and i never had a problem unless i wasnt running 91 octane. Now it does it even with 91. I tow alot and pull alot of steep grades seeing that rpm range alot. I dont want to damage anything, Im wondering if this could have contributed to me ejecting a plug a while ago. Thinking of returning it back to stock, or could the knock sensor be bad?

 

Did you change all of your spark-plugs at the time of plug blow-out ?

Are they all OEM Motocraft plugs (or Autolite platinum) ?

Fouled ( old and dirty ) spark plugs could be one reason for detonation .

Sometime I wonder about the same question ( about higher RPM and possibility of plug ejection) . My logic says , at higher RPMs , there is more fuel in the combustion chamber , so more fuel means more combustion gases that results in higher psi pressure in the cylinder . If weakened plug thread already exist , then it might be the right time . Though , I read some reports , some blow-outs occurred at low RPM flat driving conditions .

 

I did change all the plugs after it blew the plug, they are motorcraft oem plugs.