EFI harness options

Im in the process of gathering parts for my EFI swap (still) and had a question about the harness. Ive asked a few friends locally, and rather surprisingly none seem to have or know of any 89-93 Mustang harnesses. Ive looked in my local yards and the pickings are slim. Plenty of Crown vics, but those are SD and have the 289 firing order, so no good. I see Mark 7s from time to time, and they have the H.O., but speed density. I could just convert it, but Im not entirely sure what that entails. Im sure its not that hard, just havent done it. I was looking at the ford fuel injection website, and it shows the 91-93 t-bird, 94-5 truck, and 94-5 mustang all being the same MAF harness. Are these good candidates? I seem to remember reading that the 94-5 mustang computer doesnt work well with mods, and Im sure the harness wont simply plug into an earlier computer (correct me if Im wrong). Id rather not just buy one off ebay because I would never know it was the wrong harness until I went to put it on the car and it didnt work, or worse yet didnt work right and left me chasing my tail. Also I would like to pull one from a vehicle personally so that I know where everything goes and I can spend all day labeling, taking pictures, inspecting, etc. My other option is much more expensive, but has its merits as well. Flipping through a mustangs plus catalog they have an efi harness from Painless for ~$570. This would be nice because then I wouldnt have to worry that a previous owner let the smoke out of the harness (everyone knows its the smoke that makes the wires work), its the right one, no crispy insulation, and every terminal is labeled, and comes with instructions.

Its going into the car in my sig, which I have no plans to ever sell, will soon have a wide ratio AOD, and currently has what amounts to a rebuilt 96 Explorer motor with mildly ported heads and shorty headers. Once everything gets sorted out and I get financially situated itll get a stroker, but not for at least a couple years.

Ive had carbs that work great, but Ive had plenty that didnt. When my Comet was carb'd it never ran very well, though it had other issues as well. I later put that same carb on a stock explorer 5.0 in my Falcon, and after a bunch of work to excersize its demons, it ran much better, but still left me feeling like I was leaving power on the table. Ill probably be putting a lot of miles on the car, so some better mileage would be nice, a little wow factor would be nice, but mostly I like the fact that I can pretty much tune it once and be done regardless of weather or altitude.

I was in the junkyard looking at a Mark 7 and assessing how much of a PITA it was going to be to pull the harness, when an old acquaintance texted saying he had just pulled his Mustang harness in the process of converting to a 408 turbo with a blowthru carb. The car had a 5 spd in it, but I seem to remember him saying it originally had an automatic. Since Ill be using an AOD, can I use the a9l manual trans computer with the auto? I seem to remember reading that one computer could be used with either trans, but the other computer should only be used with 1 trans. Its been a busy few months since I was doing most of my research and reading, so my memory of the intricacies of EFI is a little foggy.

moonraker said:

AFAIK that generation of computers was unaware what tranny was bolted to the engine. so yes, you can use a9l from manual car with AOD

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Wouldnt the computer need to know the trans is in gear or not so it can adjust idle speed? Other than that, the trans operates entirely on its own like any other non-electronic trans.