firetruckmechanic

how much hp will the throttle body fuel injection support? I want to keep it and still pass california emmisions. I am going to use gt40 heads, cam headers and redo the the exhuast but keep it single.

mitch84

I hate to say this but if you have a CFI there isn't much you can do with the motor performance wise. The computer in the car does not like mods at all, and as far as I know there isn't any kind of performance chip upgrade for the computer. I think the only way to go is to get a whole EFI set up from a 86 and up mustang or switch to a carb which I doubt you'll pass the inspection. I switched my 84 to a carb because it was alot cheaper than the EFI but man it was still a pain. It's almost worth just buying a newer model.

GT350son

I too switched my 84 to carb from cfi... big PITA.. Mainly with the wiring.... Hard to find wiring diagrams that are correct or the same, had like 3 different wiring diagrams for a 1984 cfi mustang, they all showed different color wires for certain things. But on the other hand I do have a little less mpg with 650 dp on it. about 13-15 mpg with my foot in it all the time. Still have the computer hooked up due to it causing a grounding issue which I haven't had the time to fix, but as long as the ecc is hooked up the grounding issue is gone.

mitch84

What i tried to do was get the wiring for EFI from a junk yard doner(from a Lincoln Mark VII) which would have been super cool, so I ripped out my computer and most the wiring. That was a bad mistake because I couldn't match up the wiring. you can spend the money for a painless wiring kit and computer and mass air flow meter and all that good stuff which costs a million bucks or ger a fuel regulator and put a carb on it. I used a edlebrock performer cam, Airgap intake, new lifters and the car is way faster than the stock CFI set up. I just wish they made exhaust systems for this year because the tranny isn't the duoble hump like every other model! I'm going to take it to a local shop and see what they can do.

GT350son

I was lucky enough to have a double hump.. you should be able to buy one and replace it. And If your changing to dual exhaust your muffler may get in the way of the external fuel pump if you have cfi. But if you switch to carb you can just remove the external pump and put a new filter there as well. If you keep or switch to efi and put dual exhaust do the same thing with the external pump (put filter in its place) and get a high pressure pump for the tank.