Skip to main content
Topic: 86-88 ECU Harness Differences? (Read 162 times) previous topic - next topic

86-88 ECU Harness Differences?

What are the differences in the ECU harness in the 86, 87, & 88 cars with regards to the V8 multi-port fuel injection?  I know they are all speed density but are there any wiring or connection differences?  I say this as my experience with injection is on Mustangs and there are six different ECU harnesses.  One for the '86 cars, one for the 87-88 cars (88 California cars are the same as the 89 cars due to mass air), one for the 89 cars, one for the 90 cars, one for the 91 to 92.5 cars and then one for the 92.5 to 93 cars.

86 - non mass air, non air bag, and dash harness connection is specific to this year
87 to 88 - non mass air (except California cars), non air bag, and dash harness connection is specific to these years
89 - mass air, non air bag, and dash harness connection is specific to this year
90 - mass air, air bag, and dash harness connection is specific to this year
91 to 92.5 - mass air, air bag, dash harness connection is specific to these years (two plugs), and there is one relay under the MAF and one under the driver seat (fuel pump)
92.5 to 93 - mass air, air bag, dash harness connection is specific to these years (one plug), and there are two relays under the MAF (fuel relay moved)

That was a lot of crap most here could car less about but I have always wondered what the difference is in the V8 injected Birds and Cats.  Again, I am pretty sure that the 86-88 V8 are injected and they are all speed density but do these cars also have a dash harness connector(s) just under the brake booster and by the EEC test ports?  Were any of the late 85 V8 cars injected?

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Re: 86-88 ECU Harness Differences?

Reply #1
What are the differences in the ECU harness in the 86, 87, & 88 cars with regards to the V8 multi-port fuel injection?  I know they are all speed density but are there any wiring or connection differences?  I say this as my experience with injection is on Mustangs and there are six different ECU harnesses.  One for the '86 cars, one for the 87-88 cars (88 California cars are the same as the 89 cars due to mass air), one for the 89 cars, one for the 90 cars, one for the 91 to 92.5 cars and then one for the 92.5 to 93 cars.

86 - non mass air, non air bag, and dash harness connection is specific to this year
87 to 88 - non mass air (except California cars), non air bag, and dash harness connection is specific to these years
89 - mass air, non air bag, and dash harness connection is specific to this year
90 - mass air, air bag, and dash harness connection is specific to this year
91 to 92.5 - mass air, air bag, dash harness connection is specific to these years (two plugs), and there is one relay under the MAF and one under the driver seat (fuel pump)
92.5 to 93 - mass air, air bag, dash harness connection is specific to these years (one plug), and there are two relays under the MAF (fuel relay moved)

That was a lot of crap most here could car less about but I have always wondered what the difference is in the V8 injected Birds and Cats.  Again, I am pretty sure that the 86-88 V8 are injected and they are all speed density but do these cars also have a dash harness connector(s) just under the brake booster and by the EEC test ports?  Were any of the late 85 V8 cars injected?

From what I have seen the 87-88 Sports with the 5.0 are just for the TBirds. I have the complete set of schematics and EVTM for the 87 TBirds. To confuse you they also have the 2.3 and 3.8 TBirds on the schematics. I know I ran into a few color issues when I converted my 87 TC from 2.3 to 5.0. I used the wiring harness out of the 87 Sport and the IST kit to convert it to mass air.
To most it's easier to just bolt on a carb and shit can the port fuel injection. I can see doing it on the throttle body cars. Once you understand how the port fuel injection works it's not too bad. Where people seem to have problems is when they use a Mustang harness on a TBird. Or the A9L, A9P computers. I do not know what the difference is Mustang to TBird. The harness I used was for an automatic and used the A9L. It worked fine. Maybe I didn't have problems was because I did the MAF conversion at the same time? Unfortunately, for me, I didn't know this forum existed back in 03-05.
There are a couple of books that I found to be necessary:
Ford Fuel Injection & Electronic Engine Control, 1988-1993, Charles Probst
Mustang 5.0, 1979-1993, Technical Reference & Performance Handbook, Al Kirschenbaum
Right now I'm using a Mustang kit to convert my car from A9L, MAF to a Holley Terminator X.
1987 Turbo Coupe, 306, Trick Flow Track Heat heads, Comp Cam, Trick Flow Pistons, Eagle Rods, Center Force clutch, T-5, 8.8 w/373 gears, and a bunch more

Re: 86-88 ECU Harness Differences?

Reply #2
So the A9L's came in manual cars and the A9P came in automatic cars that were mass air.  The A9P has some additional timing in the lower rpms to help with getting the auto trans moving.  There are also issues with using an automatic car O2 harness with the A9L or a manual trans O2 harness with an A9P (https://www.corral.net/threads/a9l-with-an-aod-will-it-work.889441/).  With the Birds and Cats there were no 5.0 cars factory with a manual transmission so this is why with will work but if you stab an A9L in there you may run the risk of killing the adaptive strategy talked about in the Corral thread I linked above.

Again, I am still curious if the Birds and Cats have the interconnect between the dash harness and the ECU harness.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

 

Re: 86-88 ECU Harness Differences?

Reply #3
Man, it's been years since I compared an '87 5.0 harness to an '88...

I do remember the engine-to-body harness connectors are different between the two years, and in addition, I *think* on the '88, the headlight harness has something that makes it unique to that year only as well. Or maybe not...but I do remember that if you have an '88 and you are doing a V8 conversion, you MUST have the headlight harness from a V8 '88 Bird/Cat. Alternator harness, perhaps?

Where's Eric? He'd know for sure.
'84, '87 Mustangs
'98 Explorer 5.0
'06 Explorer EB 4.6
'11 Expedition EL

Re: 86-88 ECU Harness Differences?

Reply #4
Am I correct in assuming the '86 5.0 cars were multi-port fuel injected?

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp