Octane shorting plug

[kevink1955]

While troubleshooting my A/C problem I ran across a referance to the Octane shorting plug input to the PCM. I remember reading something about this years ago and that it reduces base timing to get rid of pinging on low grade fuel.

My Windstar has always had a part throtle ping on 87 octane fuel, the EGR ports are clean and I have just lived with it avoiding the throtle position that causes it to ping.

Anyone know where this plug is located and how it works, is shorted max timing or reduced timing.

I have always been afraid that it is pinging at crusing speed but I cannot hear it, if it is an easy fix I would like to try it.