It also had a 4bbl carb and intake but I switched to my intake and injectors. '86 mustang w/4bbl is HO correct?

86' mustangs were fuel injected. Last year for carb was 85'.

What are you planning on putting it in? (what's the non-HO?)

an '87 t-bird with AOD trans.

If the harness is from the 87 T-Bird, you don't need to replace it. I have used a harness identical to it and the engine ran fine. I imagine what is going on is the harness in the non HO t-bird and cougar engines are identical to the HO harness. Either that or the batch fired computer fires with the same frequency as one cylinder on the SEFI computer. I don't know enough about the computers to tell you. I also don't have a harness from a cougar or t-bird to look at because i don't have the cougar anymore.

Check out the colors of the wires on your harness. If there is one common color and eight individual colors (one for each injector) then it is an SEFI harness like the HO's. I would guess that is what is going on.


PKRWUD - You seem to know a lot about the different configurations of the 5.0 motors. Why don't you check into a wiring diagram on a 87-88 T-bird / cougar.

My harness has one common color for the eight injectors which I'm guessing would be a ground or "return"? wire. Then the four inj. on the left side have a common color going to each. The four on the right side have a third common color going to each. On my computer it says EFI not SEFI. So I guess I have batch fired not sequential. Maybe I wont screw around with the connector. I'll see how it runs first.