On my 89 F-150, I'm having a hard time seeing how the wiring is going to work for the mass air. I saw that one dudes website where he rigged up his own harness for his truck, and it looked great. But heres my problem. My harness branches off of my engine compartment harness via 4 connectors. The engine compartment harness starts at the computer, and wraps around the front of the engine bay, and has the four connectors for the engine harness. So WTF? I get a mass air computer, and somehow wire in my injector wires? I mean huge ordeal going on. Any answers?
TImmy

 

The way I did it originally was to go to the junkyard, find myself a mass air Ford car of some kind and hacked off:

1. Mass air wiring from the MAF to the engine connector, cutting it right at the engine connector.
2. Cut off the injector harness, right at a different engine connector
3. Found another Ford car that had a nice big juicy connector under the hood with about 20 wires on both sides, and hacked that out with about a foot on each side.
4. Hacked off the EEC connector about a foot from the EEC.

Took it all home, spliced it all up, and added the necessary pins to my existing EEC connector for the extra injectors, and the MAF sensor, as per instructions similar to the one you referenced.

Then plugged the mass air computer in and viola, wiring was done. Then I started the usual "Tweecer" type editing.

You could also buy a kit to do this for several hundred dollars, or just bring a hacksaw to the junkyard and have at it.

 

If you can find a junkyard mustang harness that is in decent shape, you can remove the injector wiring completely from the injectors to the computer (MAF wiring too). You can just run the injector wiring aside from the engine/underhood harness in your truck now. The wires from the car harness should be long enough to reach the engine from the location of the truck computer with a little extra to spare.

 

If you find a complete mustang harness, just use that harness as-is if it's in good shape.

 

It won't fit or integrate into the rest of the truck harness. The computer is located in the passenger side floorboard of the mustang and the drivers side kick panel in the truck. All the components are in different places too. It's possible I suppose, but I think it would look pretty goofy and it might be hard to make it reach everything.

 

Actually, it does fit. Just required a little surgury.

what you do is flip the harness upside down, undo the tape so you can flex it, then retape it. Then two connectors are in the wrong place which you can tape "out" of the loom and it actually does fit.

everything reaches on an SBF just fine. It's very tight on a 460 however. Ask me how I know

 

That's interesting to know! I remember when I was comparing the truck harness and the car harness that it seemed like it would almost work, and like you say, just a little work and it probably would. The biggest thing that worried me was the interface with the existing truck chassis harness.

 

Yeah, that could be a trouble spot. Easier to get maf wires with pins, and the injector harness and some pins with leads, splice it together and use the existing harness for everything else.

 

Ok, so your saying overlay a new injector harness and just dissconnect your old injector wires(two wires) and leave your old connectors dangling. But what I'm looking for is a cleaner approach. I'm looking to rewire what I already have. Add some wires to my existing injector harness, and run them like stock through the engine compartment chassis harness to the computer. I looked at that one dudes remanufactured harness he made for his 88 F-150, and I couldn't even find the connectors that are between the engine harness and the chassis harness. You know the four round ones I'm talking about? Its crazy. I'd like to make it look really nice. Maybe if I find a large enough connector, I can combine those four connectors into one, and run my injector wires through that one. Otherwise what I think I'm finding, is that I need to run new wires from my injectors through one of the connectors that might have open pins, and then from there go to the computer. I certainly do not want to remove my stock harness, and put in a mustang one. that looks like a horrible hassle. I don't even know if they are structured the same. . . as in having four connectors between the engine and chassis harness. I'll find a junkyard MAF harness, and do that, that sounds perfect. But I'd really like to make this a clean setup, withouth wires and connectors lying around. Also. . . I can just repin my old ECM connector right? and then add the new wires needed for the injectors. Awesome responses guys, your making this possible for me. Thanks and sorry for the long post
Timmy

 

Yes, repin old harness as necessary.

Remove injector harness of SD system.
Add new injectors

Reloom and tape.

The only "not clean" area is the major connector between the body, and the engine, which is on the driver's side. Big squarish connector. There are no free pins in there for adding the injector wiring, so you have two choices.

Running the wires over the connector from one loom to another, possibly inserting a weatherpack connector of your choice...

Or, what I did... find a similar connector in the junkyard (F/E series, town cars, et al) and drill out the plugged holes, and insert the pins.

 

I would think that adding an injector harness going directly from the computer to the engine wouldn't look that bad. It's only nine wires that have to be run, or 8 if you re-use the power wire from the current injectors. I know what you mean about the big plugs. The earlier trucks, 87 and 88 had an engine harness that was totally separate from the rest of the underhood harness aside from the one or two plugs that connect to the dash, etc. That's why you don't see any of those things on that other website.

 

Well, you can use the original connector - there should be six positions "unfilled" but are closed at the side the wires hang out of... nothing a 3/16" drill bit can't fix. Drill it carefully and slowly... just enough to break through. If you go to far, you screw up the inside chamber that the pins bite into. Anyway, one can add the injector wiring that way, on both sides of that fat juicy connector. That's if anyone is after perfection.

For my mass-air twin-turbo 460, I just made a new harness from scratch. Was a little more work, but I've routed the wiring differently. All of the wiring goes to the back fo the engine behind the "gooseneck" of the 460, and attach to the firewall there. I have to do the truck side of the harness as of yet. The reason for doing this is not to have any wires draping anywhere near the exhaust manifolds, or above them, as with two big turbos there, I didn't want to risk the wiring getting damaged by heat.

I made the harness by measuring everything a few times, then making a 2x4 "rack" with 4" long roofing nails, which I used to guide the wires as I ran them. Then cut to fit so there isn't any bulging by the connector, then wrapped the heck out of it with automotive wire harness tape. Took 12 hours with almost constant interruptions.

 

I am confused. What is the big square connector between the engine and the body? do you mean between the engine and body harness's? if thats what you mean, I don't have one, I have four round ones. My engine harness is totally separate from the rest of the underhood harness, or I should say can be totally separated from it. with all of these words "connector" thrown around, I'm having a hard time deciphering what you are all saying. Each injector has two wires on it right? A power and another wire with runs into a common "bank." So The common bank wires are pins blah and blah, which happen to be injectors blah and blah for the MA computer. So I just dissconnect all the other injector wires that run into a the common bank wire, and run them as pretty as I can to their respective pins on the computer right? Did that make any sense? I'm thinking maybe I have it understood, but still could be way off. But these harness setups are confusing. I remember cursing my 87 harness for being so thrown together, and connected to the chassis harness in an untidy manor. And then my 89 looked so much cleaner, by having four connectors mounted on the same bracket the connect the two harnesses. But the one dude who made the pretty blue black and yellow harness didn't have those connectors at all, and his was an 88! SO whats goin on here? Thanks again for trying to help unconfuse me
Timmy

 

OK, I figured out what that one dude with the pretty harness did. I have my old harness from my 87, which is identical to the 88, which he had. The engine harness comes directly from the ECM connector. And the chassis harness branches off of that via to connectors, a big square one, and a round one. So I understand how he did his. SO mine will just have to have one extra connector on it. . . and that will be for the injectors. I'll lay it right next to the four connecting the engine and chassis harness together. Where can i get any ford replacement connectors cheap? I might be rebuilding a lot of this harness. Thanks
Timmy

 

Yes, the four round ones. I forgot you had an 91 or earlier truck. 92+ have a big square connector. Excuse my brain short.

[QUOTE=Hiflyer746]My engine harness is totally separate from the rest of the underhood harness, or I should say can be totally separated from it. with all of these words "connector" thrown around, I'm having a hard time deciphering what you are all saying./quote]

All the F-series have seperate engine harnesses. Part of the EEC and body harness might be tied together, but there are always connectors from the engine, to that harness. This allows the engines to be built somewhere else, wired, and just "mounted and plugged in".

Each injector has two wires, yes.

The speed density computer already has injectors 1 and 2 wired where you need them, you need to add wiring for injectors 3-8, or to make things neat you can just wire them all to your new injector harness

Probably what's "going on here" is one of you have a 90-91 harness and didn't realize it. Or, something like that.