ECU Issue for GT40/Explorer Swap

[gadget73]

I had an Explorer cam, but thats not really relevant.


The issue comes from having more airflow than the ECM knows about and can compensate for. The P heads and Explorer intake get you there as long as the exhaust system flows halfway OK. I've seen the same combo you're running just act braindead with SD more than once. Sometimes it runs perfectly, often it just does not.

[fivelstang4]

I never got codes out of mine when it ran speed density. It just ran stupidly. I put it on a dyno and thats why I knew it ran lean. The pinging was another big clue. The ECM's rarely go bad, but speed-density has a narrow range of what it can deal with before it gets dumb. Seems that any heads that flow enough to make use of an Explorer intake is about that limit. Mustang guys will say thats bullshit and it will do a lot more, but that has not been my experience. Maybe the Mustang ECM is more flexible than the Mark VII one, but either way I suspect you're just at the limits of what the ECM can deal with. I know mass air conversion sounds like a stock answer, but it does work. The other option is tuning, and you may not have great success finding someone to do speed density.

I am not against going to mass air. There are so many thing on the internet I am not sure where to really start. I cant come to a exact conclusion on what I feel would be the correct parts. My question is where is/what are the best pieces to get to make up the swap/instructions?

[His Royal Ghostliness]

You are asking the right people for this. Both Gadget73 and 86VickyLX have the MAF with explorer (and now Cobra for the Vic) parts, so these will be proven setups that work. Unlike most of the bench racing you'll find on many other boards...

[gadget73]

I'm running an A9M, which is effectively identical to an A9P. Its your typical 89-93 Mustang mass air ECM for an auto trans car. I'm using the stock '86 wiring harness with the MAF connector added in. I'm using a 1992 Grand Marquis MAF and air filter box (they're basically the same from 1992-2002ish), and a 98-02 air tube. The inner fender was changed to one from a 90s car to give me the air box mounts, but you can fab your own if you like. Basically the rest is the same stuff you have, Explorer upper and lower with an Explorer throttle body. All of the sensors and whatnot are stock. My car had stand-alone cruise originally, so nothing was done there. I did add in the VSS pin to the MAF computer to make it run right. I used these instructions to make it go:

http://www.lincolnsonline.com/tech/00077.html

It might do better with a different MAF, but it seems like the transfer functions on that weenie 92 MAF work out pretty good for the un-tuned ECM. I have tried other sensors with mixed results. I had one die, and 86VickyLX gave me the one thats currently on the car. I left it alone because it runs so well with it. There aren't any fancy looking parts on the car, and basically all of it you can get from the junkyard. Makes it cheaper that way, though nobody is going to open the hood and go "OOOOHHH".

[86VickyLX]

I ran an A9P with a 94-95 Thunderbird/Cougar MAF, with explorer upper and lower with no problem. I upgraded to 24lb injectors, cobra upper and lower ported with a 70mm throttle body with the same computer and MAF. Only difference being I changed the tune slightly so fuel wasn't dumping into the cylinders (MOATES quarterhorse).