Ok I have a 1988 f150 with a 5.0 302 in it that is EFI. I want to convert to MAF and in doing so gain some more power and mpg. I collected the computer the maf sensor and a fuel injection harness from a 90 mercury cougar with the 5.0.
When i started tearing into the wiring harness for the injectors from the cougar i found just as i suspected, 8 wires for 8 injectors along with one wire for the posative, no suprise. so i went to my trucks harness looked at the hookup for the injectors and WTF its the exact same 8 wires on the conector same style hookup and everything. According to everything i have been told about EFI and SFI there shoudl be only 3 wires for the EFI injectors. 1 hot wire and two going back to the ECM. this is why it 4 at a time vs only when it needs them. My question is, Am i right and i do have SFI on my truck and its just an oddball thing ( i know mustangs of this year came with it) or is there some place where those 8 wires go back into 2 and lead to the ECM. I have looked online alot and found two diffrent harnesses fot the maf conversion one for mustangs that didnt have the fuel injector overlay harness and one for trucks that replaced the injector wires to make it SFI which mustangs already had..... Please help me out im just kinda stumped right now.

any help would be appriciated
thanks

 

The injector wires are spliced in the harness . Take multi tester and check injector to wire Harness coupler.Bet you find tree wires to injectors .If cougar harrness has all senors in right place no problem with harness. But probably won't have PSteering sensor .And if injector wiring is the same no problem. That year firing order should be the same. Check and see if computer will plug into your harness(Think there are more wires because of maf in new computer plug .The difference is on the fender well harness for maf. bet different wire lay out .Get the harness of car so have needed wires for Maf to computer. And add them in to your harrness switch out truck computer plug for Cougar pluge .that way don't have to change complete harness. I sure someone will be along that knows of a after market kit of some sort. some 94 95 trucks have Maf but firing order is diff. but easy fix though. Any way you do it you'll be swuitching something.

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94 F150 4x4 super long 302 at

 

well i have read about this in a few guides on how two do it and even in the kits, they say nothing about the ecm hookup, its just wires that were never in pin slots before. I should go snag the connector anyways for the ecm, Hope fully some one else will come along that knows a little more about it. I will test the injectors just as you said trying to find if they into the same wire. thanks for the help, that solves part of the problem.

 

I'm not sure what the cougar uses in terms of wiring connections, but on the 88 truck harness I have, the injector wiring is also run with the wiring for the IAC, TPS, ACT, and ECT. That makes three wires for injectors, three sensor wires, one signal return wire, and one wire for the IAC (the power is shared with the injectors) for a total of 8 wires.

The mustang mass air harness I used to make a truck mass air harness used two 10 pin plugs for the injector wiring and the IAC, ACT, ECT, EVP, oil pressure and water temp gauge senders and canister purge valve.

The truck shouldn't be SFI unless someone has already converted it before you bought it. Do you have any pictures of the two plugs?

 

I went and stripped off the complete harness from a t-brid ho and noticed that for the fuel injectors it has 2 connectors a round one and a square one, i am suspecting that it is for the injectors. you are correct i was wrong the 8 wires are from all those sensor that are on the injector harness in the pickup my bad. thanks for clearing that up. i will update after i stip this harness and ask any further questions. thanks for the quick reply

 

Glad you got it figured out, and good luck with the swap!

 

lets see if you guys can figure this one out. according to my sources i should wire my injectors in a diffrent order then as if i were doing this conversion on a mustang with a roller cam.....which the firing order is diffrent on. here is the way i was told to do it via diagram

pin# injector firing switched to fire injector #
13 4 7
15 6 6
14 5 3
59 2 2
58 1 1
42 7 4
12 3 5
52 8 8

this seems to make sense to me, now i have all 8 injector wires in the proper places on the ecu connector now add the 2 pins for the maf then swap all my pins from my harness to the new one minus pins 58 and 59. then make sure i have the posative lead for the injectors in pins 57 and 53. install an o2 sensor in the right bank manifold or just splice the signal wire into pin #43 to simulate having 2 o2 sensors. then plug the harness intot he new ecm, hook up injectors and maf connect batery then give it a whirl. so does this sound right am i missing anything??

sorry about the typing, i know i type two quickly and sloppy when im tired. if you cannot understand it just say so and i will try and explain in better.

thanks for the replys

 

Sounds about right, but remember that you will have to move the pins for the TAD and TAB solenoids as well. The computer still needs them, but the pin locations are different between the truck and the cars. The injectors look right to me, and I would say just split the single O2 sensor signal to both of the input pins on the computer.

 

Ok good, I figured since im swaping the injectors around the the computer it might even confuse it even more if i had 2 o2 sensors reading 2 signals it could get kinda screwy. why make it any more complex. Yes I will saw the TAD and TAB solenoids although i dont even have them installed anymore, I removed my smog pump and all the equipment. As soon as the intake arives I am going to get this done i dont think it will really take me all that long, its just 10 pins and 4 splices. If anyone has any advice for me, something i am overlooking just notify me please.

thanks everyone