92 F250 5.8 Manual Trans Efi
Need To Change From SPeed Density To Mass Air Flow And I Was Told I Could Use Parts From A Mustang But I Would Need To Overlay THE Wiring Harness--- That Is Where The Knowledge Dries Up. Can Anyone Help?

 

Well first off, why are you changing to mass air? Have you got some serious hot rodding ideas... cam, heads, bigger injectors? I have the FMS mass air package but it's not really necessary for the mods I have at this point.
To answer the overlay question. The Mass Air Stangs fire the injectors sequentially, while the truck fire them in banks of 4. So you need the injector harness from the stang and you need to "overlay" it on the existing truck engine harness. What really needs to be done is you have to add a wire back to the computer for each injector, and you have to add wires for the mass air meter as well. Believe it or not it's pretty easy to pull these wires from the computer connector with pins attached, then all you have to do is plug them into your computer connector in the right place. Both computers use the same connector, and obviously the mustang uses more pins because of the things mentioned already, and because it also uses two O2 sensors.

 

As for they why question because hewants to. And what above milage improvment
I have done a few . Is your truck the newer body style?

You will need ECM , 94 up maf F150 harness from cab to injectors. 302 wiring is same as 351 .Grab Maf and air box .Take your 93 harness & new Maf harness Split. take all Ecm /engine related wires plugs and put them in your harness .As the plug is different for ECM on yours. Leave all cab plug the same. That way you can do away with all airbag wires and use your 92 cab harness for lights ,ect. The wires can be removed from plugs easy enough. You can just remove wires needed and insert in you 92 cab plug .Get a good wiring diagram. Just do some research or get a overlay harness kit. Post back for more info.