cfi to efi ho

[tim marks]

finally got to drive my 84 on the road this afternoon, first time since i put the duals on. brought it home from work with the repair towing tags on it since i have yet to register it....

its got no guts! i dont remember my other ones being so gutless.

now im getting impatient, im thinking of going efi ho. scott keeps telling me i should, but i was hoping to build up the cfi. now im not sure. ive read a few of the stickies here on efi conversions and i have most everything i need in the shed already. ive made a list of things i need to get yet that i dont have. there are a few things im not sure of since i have an 84

i know i need a wiring harness, preferably from an 86-87.
ho upper and tb, injectors, bored egr, air cleaner box

would i be best with a mustang computer or a mark 7?

also, am i right in figuring i need an efi throttle cable, TV cable and shift bracket, and a canister purge solenoid?


is there anything im missing?

if the stars align i could be running by SF09......

[85crownHPP]

Dont forget the fuel lines... using the 90-91 harness was pretty easy for me, I cant see the 87-89 harness being any easier. The newer harness definitly makes for less clutter in the engine bay.
I think you cant use a roller cam with your 85 block - keep that in mind when you look for a cam.

[88grandmarq]

Most all 85 blocks are already set up for Roller cam and are roller compatible.

[Lincolnmania]

he has a 84 tho.

[85crownHPP]

oops, my mis-read

[Leo]

Soon to be a CFI defector huh??!! I'll agree cfi's are on the slow end....
I raced against my brother who has a lopo 91 CV. That miserable bastard kicked my ass... I admit, I was impressed with the efi.
But ill stick to the CFI's, hopefully soon HO CFI

[gadget73]

The 88+ harness has integrated cruise stuff. You won't be using that crap, but it does have the VSS inputs, which are useful. You'd have to find a way to piggy-back the inputs though. I made a small jumper harness for mine that goes between the trans harness and the car's main harness that gives me VSS to the ECM without cutting anything.

[85crownHPP]

do you know how the ECM uses the VSS info?? I didnt wire mine into the ECM harness since my cruise is independent... I shall if I should.

[tim marks]

i have a 91 HO donor motor so im not worried about the roller/non roller situation. do you have documentation of how you jumped to VSS to the ECM? how about o2 sensors? im guessing i will need two, correct? were they different from 84 to 87-91?

[gadget73]

do you know how the ECM uses the VSS info?? I didnt wire mine into the ECM harness since my cruise is independent... I shall if I should.

not 100% sure, but I suspect it has to do with the egr action. I had an off-idle hesitation that I could never fix. The EGR valve also started to open immediately above idle speed, which I suspect was wrong. Unhooking the egr took away the hesitation, so the only thing I can come up with is the ECM was just opening the thing based on throttle position, and not on throttle position plus vehicle speed. The lopo ECM, at least on an 86 or 87, does not use any VSS input, so it ignores that. Might even be that no lopo ECM uses VSS for anything but cruise. The Mark one, I don't know. I always meant to wire in the VSS stuff, even added the pins to the ECM connector, but I never connected them to anything so I can't honestly tell you if that would have fixed my problem. It had extensive a/f issues and ran really lean, so it may have been something else causing the problem.

[gadget73]

i have a 91 HO donor motor so im not worried about the roller/non roller situation. do you have documentation of how you jumped to VSS to the ECM? how about o2 sensors? im guessing i will need two, correct? were they different from 84 to 87-91?

I don't document much, and its slightly different on a Towncar anyway. On a Vic or GM, there is a two pin connector alongside the 4 pin one coming up from the trans. i think the wires are green and black. Basically what I did was cut both a trans side and car side connector out of a junkyard car and connect them together, making a 6" extension that sits between the stock connectors on my car. I tapped wires onto the extension and ran them to the proper pins on the ECM connector. Its slightly hackish, but it was the easiest way to keep my ECM harness removable from the car without having to cut anything.

Need 2 O2 sensors, and they are different. early ones are 1 wire, 86+ is a 3 wire. 88+ ones have different pins too, and I think they're slightly cheaper. Same sensor, just a different plug. grab the O2 sensor harness out of a junkyard car, its a Y shaped thing with one rectangular plug into the ECM harness, and the two O2 plugs at each end.