I have a 1991 F150 5.0 4x4 w/ an E4OD. I'm not sure what the motor came out of. There was a slight miss at around 1500-1700rpm only when cruising that would go away when accelerating or decelerating. I replaced the plug wires, distributor cap and rotor button. Previous owner said he had just replaced the plugs, but I decided to pull and inspect them anyway. All but 2 looked pretty good, so I went to the parts house to get 2 more. The truck should use Motorcraft ASF-42C (SP450) which is what the sticker under the hood called for. Well they wouldn't even thread in. The plugs that came out were AGSF-32C (SP447). These would be for a mid 90s Cobra or a 5.0 Explorer. There are no GT or GTP markings anywhere on the heads. Pretty sure they are E6SE heads, so I went and got some Autolite 2545 plugs, gapped to around 0.046 and installed. Seems to be running better now, but the CEL came on and I am getting a 225 code, which is the knock sensor. I need some help.

 

Did you knock the wire off the knock sensor or damage it when working on it?

You replaced the plugs, wires, and rotor - why didn't you replace the distributor cap?

 

I did replace the cap. I did the plugs, cap and rotor a while back. Didn't have the knock code until I did the plugs. I don't think I knocked the wires off or damaged it, but I'll recheck. The light doesn't come on at idle, but only after I start driving. I'd say it comes on within 1-2 minutes of when I start driving.

 

225 Knock sensor (KS) -no signal during KOER dynamic response test
Probable cause: Wiring, KS, ECM

 

Re-ran the test and the code is gone now. Go figure. Thanks for the help though.