The only reason to switch would be so that you can easily use an add on tuner like the Tweecer RT or any other tuner that uses the J3 port. If you switch to this ECM without those tuners you also need to get a MAF from the same model year of Mustang and you need to relocate your ACT to the intake tube (which you should do anyway in this switch). You can use Megasquirt or almost any other tuning system as well. It's all really about personal preference.
Honestly, at this point the model years in question (91-93) are between 16 and 18 years old and if you are still using the car as a daily driver you would be better served to just leave it alone. If you are wanting to make it into more of a race car then I would recommend rethinking just about everything you are considering since this platform isn't very friendly to goals like racing. Just get a Mustang and your life will be easier.
1. The car has been permanently retired as a daily driver as of March 4th, 2008....the day my mother passed away, and it became mine. In addition, the car isn't going anywhere, so in a good way, I'm stuck with the car. In addition, all I ask is that I not be associated with 'Twin-Turbo 281' types of builds, as I'm probably one of the most detail-obsessed auto mechanics out there. Hack-job cars set my teeth on edge....
2. It's not going to become a race car, it's simply going to be a nice street driver that's going to be more aggressive than stock....and whatever will be done with the car has to be reversible, or doesn't butcher the car to the point where it can't be driven, or changes the car to where it's unrecognizable or undrivable. I actually started on this car some years ago, back when my Mom still drove it ( I bought it for her in 1999), and most of what I'm doing was something her and I discussed doing already. However, as new or improved parts become available....
3. I'm rather familiar with what can and can't be done with this platform; I've already done an extensive amount of work to this car (with more to follow), and have performed repair, restoration, and modification work to countless other vehicles, no small number of them being my own. This particular bit of research is an attempt to fill a small hole in my knowledge curve about the Mustang ECM suggested as an easier-to-procure replacement for the rather-difficult-to-find OEM T-bird ECM. Initially, the first problem I'd like to eliminate is the issue of the stock, almost irreplaceable stock ECM. Second, If there is a better solution (Megasquirt, or similar), while I don't profess being an expert about EFI in general, and don't tune EFI cars, I do have a pretty good grasp about how the stuff works; I'm simply out of the loop concerning the computer-tuning end of the spectrum....and I want to know if there is something out there that is better for what I'm trying to do.
4. While I might give the appearance of darting all over the map concerning what I'm going to do with this vehicle, I actually have a solid build plan
for this car as to what is going to be done with it. The engine I'm building (long-rod 302 with some interesting modifications) is almost completed, and about 50-60% of the new/rebuilt/modified parts have been procured. This engine combo will require tuning to maximize what I'm trying to do with it, and if the T-bird ECM is a weak link....then it's going to be tossed. And if the Mustang ECM only has a few possible tuning maps to choose from....I'm not even sure I want to go down that path, either, as the only 'touchy' part of this combo is going to be ensuring that I have a conservative timing curve. That's why I'm asking questions about how 'tunable' the Mustang ECM is now, instead of after bolting everything into the car, and then asking why the Mustang ECM won't adapt to what I'm trying to do....
5. I already have an Exploder intake, and due to the lack of an ACT hold drilled in the lower intake, it's already in the works to relocate it. In addition....I already have a couple of Mustang MAF units in the pile of parts (94 and 95).
6. If this becomes too big of a pain in the rear to settle....I can always go carbed. As I stated, this car has been permanently retired from daily-driver status....and to be honest with you, something has been lost with EFI, in how sluggish most EFI cars I've either owned, worked on, or driven are, in comparison to a snappy, properly-tuned carbed vehicle. One of my favorite carbed cars that I owned was a 1985 Mustang GT (5-speed)....after spending a few weeks tuning a turd Edelbrock carb (not as easy to tune as advertised)....I loved driving it. My only complaint was the road noise was a bit unbearable on long drives....and Edelbrocks aren't as good of a carb as some of the better offerings out there. This is 'plan B' of course....but it's workable.
7. Do a Mustang? I've already owned seven....a big-block '79 Cobra, 82', 83', 84', 85', and 1989 GT's....a 1984 Coupe, and...I'm forgetting the last one....With the exception of the ECM problem, I have a definite plan for this Bird....and I like the way it feels on road trips. This car is incredibly stable up to 100+, whereas the Mustangs and other cars that I've owned....weren't. With the exception of the seating problem that I'm working on....I like driving it long distances....where I couldn't get out of any of my Mustangs fast enough (or other cars that I've owned).
Does anyone here have any Megasquirt experience?