I'm helping a neighbor change head gaskets, 88' F150 5.0 EFI, and on the passenger side rear of block there is a sensor. It was broken. I cannot find any info in my books. Can anyone tell what it is and what it's for? Also it's on top right behind intake.

 

That is a knock sensor, you may have to source one from the scrapyard as I believe they are out of production.

 

Yeah that's the knock sensor and if you can't find a replacement you don't really need it anyway. Plenty of people leave them disconnected without problems, just make sure your timing is set right.

 

Thank you, that helps a lot.