What is this??!!?
PostFri Jan 27, 2017 12:54 pm

I just inherited a 98 f150 4.6 v8 romeo. It had been setting in a field for over a year and field mice found it a great home. They chewed off #4 plug wire which was an easy fix. However I also found 2 wires chewed through....I'm not sure what it is or where it goes! It has two wires (black and white) heat resistant cloth type cover and it goes into a plug behind the #4 spark plug. It looks like it has some type of sensor attached to it or by it.
I tried to get pics but I'm sure yall lnow the the joys of the #4 plug on the 4.6 v8!
Thanks for any help!

 

If the wires are next to the spark plug it could be the fuel injector wires.

 

Thanks for the reply! But all injectors are accounted for..this seems to be mounted to the block and not on the injector rails! I should've mentioned that in the post.

 

Maybe the knock sensor or the wire that goes to the O2 sensor?

The knock sensor is under the intake manifold....

 

There isn't any solid white and solid black paired on the vehicle harness...so it has to be a sensor pig tail. Only two pigtails like that I recall. One is the RFI, the other is O2 (2 of 4 pair).

It's most likley RFI...capacitor pigtail. They either route to the manifold or front of block. It depends whether you have a metal intake or not.

 

Thanks jbrew! Can I ask what RFI stands for?

 

Radio Frequency Interference. There is two of these on your truck. Same locations opposite of each other. So you should have another one on the opposite side of the engine to compare to, if your missing one.

However that might not be it ? I'm thinking they only have one wire (Black). Iduno, can't remember now..check it out anyway.

 

Diffently 2 wires 1 black 1white. I didn't see a second on the driver side...just the one connector way back by the firewall by #4 plug. It's not throwing any codes since I replaced the d4 plug wire but is still running rough at all speeds...but no codes! This is driving me crazy! Albeit a very short drive!

 

Are they factory ? Is there any reason you can't trace them. Tracing would be definite or did the mice feed on your wires to the point it has no routing ? I'd just trace it, see where goes of comes from...why haven't you ? problem ??

Also make sure the wires are stripeless. If they are striped, it would be an easy lookup.

 

Yes they are factory solid black and white with some sort of cloth type sheath. I traced it back to a connector that is mounted on the block behind #4. I guess it's not where it ends but where it originated. I looked everywhere for orphan wires..but nothing.!