Fordfoxbody88

hello i have a 92 foxbody mustang lx that was a 4 cyl i then did the v8 swap with it and have a 86 302 ho in it. i took the 4 cyl ecm out along with all the wiring to the 4cyl motor, what i now would like is some help from you guys as in what ecm i need for the v8 and if theres one for the v8 motor that will plug into the 4cyl old ecm plugs or if theres some way i can get something to replace a stock ecm or what i need.then just i need to know everything that i need to know

reldla1996

You'll need a computer (ecm) from a 5.0 Mustang and matching wiring harness that goes from the computer to the engine bay along with all the appropriate sensors. Here's something I wrote right after converting my 89 from a 4 cyl to a v8 -- On electronics, they are totally different, almost everywhere and every single item. The wiring harness under the dash is the same, but that is about it. The computers are different along with the wiring harness that goes from the computer through the firewall and then various places. The wiring harness going from the coil area up and around the radiator to the alternator and the engine wiring harness are also different. The engine wiring harness is also different. The barometric sensor is different. The V8 also has a EGR vacuum regulator, TAB solenoid, and a TAD solenoid mounted on the back side of the right shock tower that the 4 cylinder engine does not have. The coils and starter motor relays are the same. One last comment is that the computer, wiring harnesses, and sensors should all from the same year, or you may have to do some adapting to make it work. Don't be daunted by all the various wiring connectors, they are all unique and will only plug into the correct mating wiring connector (except the 8 fuel injector connectors). You'll also need a v8 tach, or easier yet, the whole v8 instrument cluster. Otherwise your tach will be off by a factor of 2.

Fordfoxbody88

okay so how do i get power to computer? will the computer hook into the old power wires that the 4cyl had or what do i have to do there? i know i need a different harness to go with all the other sensors but i guess what im asking is what year computer do i need for my 92 because i heard some wiring was changed between 89 and 90

Mike T

Any A9L ECM from 89-93 if you have a T5 transmission, A9P if you have an automatic. You'll need the corresponding harness to go with it, new or used if it's in good condition. You can't use the 2.3 harness, it won't work.

Fordfoxbody88

okay well where do i find all the wiring harness then lik the one for under the dash that plugsinto the computer tthe one that plugs to all the sensors under the hood cant be unpluged from the computer right and how do i tell the difference between the two computers

Mike T

They sell the ecm at all the major chain auto part stores. If you have an ebay account I would check there for the harness. The ecm's are labeled A9L or A9P. Here's an example...http://www.ebay.com/itm/1993-MUSTANG...e0b418&vxp=mtr

Mike T

You can also get the harness at a junkyard, just make sure they'll guarantee it to work.