EFI for my 1979 Cobra

myles

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I have a 1979 Cobra and a 1997 explorer 302 engine with all the stuff on it. I would like to put it in with the painless wiring harness. I have some misc 87+ mustang EFI parts about but I need to know what parts will be needed. I have a gas tank from a donor 87 lx 5.0, I also have a left over throttle body from my 95 Cobra. The painless kit tells me I need the Ford Motorsports comp, but I think I can get a MAF ECU from a later year mustang? I am also using a T5 trans if that matters. Are the injectors on the explorer 302 going to be an issue? I am trying to do this on a buget with junkyard parts when possible. But I also know that it is smarter to buy the right stuff in the first place, so I don't mind being given suggestions on parts I should just buy and not mess around with old stuff. I know there is some post in mags and forums so that info is appreciated also. I also know for some reason the 1979-1980 mustang gas tank is unique and am curious if this 87 lx 5.0 tank will bolt in or not.
Thanks
Myles
 
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jrichker

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The Explorer 19 Lb injectors will be just fine, they are supposed to be better than the stock 5.0 Mustang injectors.

List of computers that will work without modification:
A9L - 89-93 5.0L Mustang 5-spd
A3M - 93 5.0L Mustang 5-spd
A3M1 - 93 5.0L Mustang 5-spd
A9P - 89-93 5.0L Mustang Auto
A9S - 88-93 5.0L Mustang California
C3W - 89-93 5.0L Mustang Auto

You may want to use the Ford Racing M-12071-A50 harness. It is one piece from computer to injectors and has all the connections for ignition, MAF, and sensors.

Websites you should bookmark:
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for94-95 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

AutoZone wiring diagrams

For 79-88 model Mustangs
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528004e28c

For 89-93 model Mustangs
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c15280069677

For 94-98 model Mustangs
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152801f5e3b

For 1999-2005 model Mustangs
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152801ef7d7

http://www.fordracingparts.com/home.asp
Download the catalog. You will need the Adobe Acrobat viewer which is also a free download – Adobe - Adobe Reader download - All versions
 

93 LX

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jrichker,

If you use the FORD wiring harness will changes need to be made to it as doing it from SD to MAF, since this is what I will be doing when pull the engine on my 86.
 

jrichker

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jrichker,

If you use the FORD wiring harness will changes need to be made to it as doing it from SD to MAF, since this is what I will be doing when pull the engine on my 86.

Ford Racing's notes on the harness say that it uses a 89-93 Mustang computer. That means it is a Mass Air system.
 

jrichker

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Yes I know, I was talking about doing the MAF conversion with this harness. Is this a way to go instead of modifing the old harness?

Not unless you have major $$$. The $30 for a conversion kit is a lot cheaper than a $450 harness.
 

myles

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How about this? I have a 87 LX 5.0 donor car in my yard. Would it make sense to convert it to MAF and use it's harness on my explorer eng and 79 cobra? I am not super smart with wires but may be able to figure it out if there was some tech on it out there.
 

jrichker

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How about this? I have a 87 LX 5.0 donor car in my yard. Would it make sense to convert it to MAF and use it's harness on my explorer eng and 79 cobra? I am not super smart with wires but may be able to figure it out if there was some tech on it out there.

MASS air conversion instructions from MAF - Mustang Mass Air Conversion - StangNet - The Mustang Network FREE
A9L (5 Speed) computer from junkyard $100-$150
A9P (Auto or in a pinch, 5 Speed) computer from junkyard $100-$150
70MM MAF from 94-95 Mustang GT - $40-$70
MASS Air wiring harness kit $30-$85

The whole thing is probably less than $300 using junkyard parts.

The conversion harness seems to work well for most folks. It avoids the compatibility problems in using a harness from the junkyard. Simple and cheap, it is actually less work that swapping the wiring harness. I have pulled the stock harness out of a wrecked car and it was like wrestling a big python.

Conversion Harness kits & parts
Interactive Systems & Technologies Mass Air Home Page
Ford Fuel Injection EFI Harness Pigtails

Larger MAF to go with Mass Air conversion:
94-95 Mustang GT MAF - $40-$100. It is 70 MM instead of the stock 55 MM on regular stangs built prior to 94. It uses a slip on duct on the side that goes to the throttle body and a 4 bolt flange on the other. You need a flange adapter to fit the stock slip on air ducting that goes to the air box. Wiring plugs right in with no changes. *1 *2

*1.) Metal flange adapter Kurtz Kustomz Motorsports, Inc. KKM Buy the TR70 for $44.95. Or spend some time on eBay looking for one that may fit.
Try AutoZone and ask for 81413 - Spectre / 3 in. Aluminum Intake Mass Air Flow Sensor Adapter at $12.00. You may have to order it online.

*2.) MAF & sensor interchange
The 94-95 Mustang 5.0 MAF & sensor is also found on:
1995-94 Mustang 3.8L F2VF-12B579-A2A,
1994-92 Crown Victoria 4.6L F2VF-12B579-A2A,
1995-94 Mustang, Mustang Cobra 5.0L F2VF-12B579-A2A,
1994-92 Town Car 4.6L F2VF-12B579-A2A,
1994-92 Grand Marquis 4.6L F2VF-12B579-A2A,
Evidently the –A1A, -A2A, AA, etc. on the end of the part number is a minor variant that did not change the operating specs. You should be able to ignore it and have everything work good.
 

1stanger1

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everything is pretty much self explanitory all you gotta do is use a harness from a fuelie 5 liter and sounds like you got all the bolt on parts but as far as an ecu like jrichker said an A9L is your best bet but i think you'll find that they are a little more than that unless your dealing at a salvage yard that doesnt know squat about cores like i do i know that a junk one is $100 at least thats what i pay for them with a good case

there are alot of years you can get these ecm's from you could even go with a 95 ecm i heard it has a slightly higher rev limiter at least thats what i am told but
so far everything sounds right on par.....
let us know how it goes and we'll be here to guide you along your journey! have fun
 

jrichker

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there are alot of years you can get these ecm's from you could even go with a 95 ecm i heard it has a slightly higher rev limiter at least thats what i am told but
so far everything sounds right on par.....
let us know how it goes and we'll be here to guide you along your journey! have fun


The 95 computer is a different animal and will only work with a 94-95 Mustang harness. The tune on the 94-95 computer isn't as user friendly as the 89-93 models.
 

myles

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Bit of an update. I have a A9M comp from a 90 and all the harnesses from a 90 5.0 with some sensors coming to me from a friend. I will attempt to figure this out, but if it gets to be to much, and it prob will. I will just buy the ford motorsports harness. I have the efi tank and the whole wiring harness from the donor 87 lx 5.0 so I have some parts. I also kept all the fuel lines too.
thanks for all the info everyone

Myles


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jrichker

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Bit of an update. I have a A9M comp from a 90 and all the harnesses from a 90 5.0 with some sensors coming to me from a friend. I will attempt to figure this out, but if it gets to be to much, and it prob will. I will just buy the ford motorsports harness. I have the efi tank and the whole wiring harness from the donor 87 lx 5.0 so I have some parts. I also kept all the fuel lines too.
thanks for all the info everyone
Myles

The computer is OK, but the 90 computer harness is a bit of an oddball item. The harness has dual dash connectors and wiring for the airbags which tend to confuse things. You probably can make it work, but several of the connectors will need to have pins moved around to make it plug compatible with the dash and body harness.

I don't have any details of what needs to be done, so someone else will have to assist you on using the 90 computer harness.
 

myles

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If I have to much trouble with it (and I'm sure I will) Can I just suck it up and get the M-12071-C302 harness? I think it's around 200 bux. I already have the injector harness.
thanks
Myles