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thats wat i read...because i have a 89 gt donor for my 93 lx and it wont work...only a mid 92 and 93 harness will work for my swap
 

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well i have a good complete 89 harness that i wont need well i have a complete 89 vert harness front to back minus the trans and engine harness that i wont need if anyone is interested...
 

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Differences in EFI Harnesses for the 87-93 FOX

This ought to explain it !

87-89 (EXCLUDING California Mustangs, which in 1988, were MASS AIR), are Speed Density. To Convert these to Mass Air, you "have to have" an EFI Harness from a 1989 Mustang or one from a California 1988, ONLY! The only other option is to buy a Painless Wiring Harness. NOTE: The 1988 Calif. MAM "Plug" is OBLONG but can be converted to the OVAL Shape with the Newer (oval) Connector.

Now, from here on in, this information is for the purpose of Converting a 4 Banger Mustang (I DO NOT CARE If it is a COUPE, HATCHBACK or a CONVERTIBLE)! AND, I could CARE LESS "What You Have Been Told"! I've done HUNDREDS of these Conversions MYSELF and "I" have been doing so for the past 20 plus Years!

87-89 Use a 1989 EFI Harness. How do you tell? It will have the Round Gray and Round Black Connectors near the Brake Booster BUT, NO WHITE Connectors anywhere on this Harness (other than the big White 10 Pin Connector). It will also have the MAM (Mass Air Meter) Connector on it.
NOTE: If you find a Harness that does NOT have the MAM Connector on it, it is "most likely" a Speed Density Harness.

1990 is a "one year only" Harness. How do you tell? It will have the Round Gray and Round Black Connectors (just like the 87-89) near the Brake Booster, but WITH 2 Little White Connectors (for Air Bag Sensors) on the Harness near the MAM. Build Date of the car will be LATE 89 or within 1990.
NOTE: NO, you cannot use this harness on a 87-89!

91 through Mid 1992. How do you tell? It will have a Brown Connector near the Brake Booster. Due to Factory "Overlap", look also for the Fuel Pump Relay that will be a Black/Green "BOX" under the Drivers Seat. If it is not there, you have a Mid 92 through 93 Harness.

Mid 92 through all of 1993. How do you tell? Look for the Brown Connector near the Brake Booster but also Confirm that it Does NOT have the Black/Green "BOX" under the Drivers Seat. Also, Confirm that there ARE 2 Black "Boxes/Relays" by/near the MAM.

QUESTIONS? Feel free to e-mail me at [email protected] Don't bother trying to make it sound like you want to buy something. I don't care, tell me what you want to do, and or confirm.
YES, I have ALL of the Harnesses that you will need and/or Information! I just ask that you do not waste my time.

OK, I just flipped through a lot of the responses prior to this post and find that people are trying to Mix N Match Wiring Harnesses.
I'll make this really simple.
If you want to do a job and do it right, use the Right Harnesses! If you have a 1990, use 1990 Harnesses. If you have a 1993, use 1993 Harnesses.
When doing ANY Conversion, is is NOT Necessary to change the Dash Harness as long as you use the MATCHING Year Harness/es!
Got questions about this, and I know some of you do, feel free to e-mail me. [email protected] 23 + Years of experience doing STOCK Parts Conversions of all types.

Doing an AOD to T-5 Swap? There are a couple of Wiring changes that need to be made but you still DO NOT need to change the Dash Harness!

Doing A 4 TO 8 SWAP? See my 4 to 8 Swap Parts List 87-93 Mustang on page 7.

Jon
 

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If you change from a stock 4 cylinder K-member to a Team Z Tubular v8 K-member....
if you want to keep power steering you will need either the stock power Rack and pinion, or one from AGR...the Flaming river one does not work with the team Z tubular K-member.

also, you will need a V8 Steering shaft...the 4 cylinder one is shorter and it will not reach once you put in the v8 k-member
 

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Hey Guys, i'm planning on doing a 4 cyl to v8 swap. I have an 89 4 Cyl hatchback and a donor 87 5.0 hatchback both 5 Speed. My plan was to just gut both and swap one into the other, absolutely every single harness but would it be possible to just use the main harness and computer off of the 87 without ANY setbacks? Would everythig work in a plug n play manner?
 

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Hey Folks, I have a 90 LX Manual that I am converting to 8 cylinders. I engine is from a 93 LX, the Harness is from a 90 and It is the correct harness with air bag connectors and one relay by MAF and fuel relay under the seat. I have everything connected but the car will not start and fuel pump seems to not be coming on. If I jump the solenoid the start will turn the engine but not from using the key. I am not sure what to do next. The car would start when the 4cylinder was in it although it ran rough. This car was sitting since 97. What steps should I take next?
 

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Check for the starter solenoid activation wire, should be red and blue I think. If thats getting 12V when you turn the key then there's a problem somewhere. The fuel pump not activating could be a number of things from bad relay, to the fuel pump cut off in the hatch, to bad eec relay, to the computer being bad.
 

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Hey guys, I have a 89 4 cylinder that I'll be conversing to a v8 from a 91 donor. My mechanic experience is very limited and I'm just worried that I'll end up with a car that won't start. Can anyone link me to a maf harness that I can purchase, that'll work and make my job easier as I feel like I'll have setbacks with the 91's harness. Thanks.
 

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Discussion Starter #411
Hey guys, I have a 89 4 cylinder that I'll be conversing to a v8 from a 91 donor. My mechanic experience is very limited and I'm just worried that I'll end up with a car that won't start. Can anyone link me to a maf harness that I can purchase, that'll work and make my job easier as I feel like I'll have setbacks with the 91's harness. Thanks.
Try Ebay, Craigslist, internet search.

Cant believe this thread is still going, wow.............
 

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Hey guys, I have a 89 4 cylinder that I'll be conversing to a v8 from a 91 donor. My mechanic experience is very limited and I'm just worried that I'll end up with a car that won't start. Can anyone link me to a maf harness that I can purchase, that'll work and make my job easier as I feel like I'll have setbacks with the 91's harness. Thanks.
1989 Mustang GT LX 5 0 Mass Air ECU Harness | eBay
 

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I have an 87 LX doing the swap with a computer, and harness from an 89. will I need a new headlight harness? and if so what other years other than an 89 will work?
 

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I have an 87 LX doing the swap with a computer, and harness from an 89. will I need a new headlight harness? and if so what other years other than an 89 will work?
87-89 V8 headlight harness

You only need this because the alternator circuit runs through it, and the plug is on the passenger side for the V8, compared to the driver side for the 4 cyl.

You could just extend the alternator wiring.
OR
As some people do with the 130 amp 3G swap, just run a new , thicker alternator circuit.
 

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You could probably make the fuel lines work, but it would be easier to just get a teh 5.0 lines from a 5.0 car and swap them in. all of the mounting points for the 5.0 lines are already on the 4 cyl cars.
Good to find this, picked up a wrecked 86 GT parts car, getting an 85 coupe soon, wondered if the fuel line pedestals were the same, couldn't imagine them having to put different ones on at the factory, but they've done stranger stuff
 

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'97 351w efi into '93 notch

I've got a 4 cyl '93 notch. I've got a '97 F250 with a 351w. I've done the swap on a carb setup but I'm wondering about swapping with EFI. Could I use the truck ECM and engine harness?
 

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I have searched and not found the specific answer to this question, so excuse me if it is basic or if I missed the answer. I have found an '82 coupe with a 4 cylinder. I want to convert it to V8. I have found numerous 89-95 V8 mustangs (rusted, wrecked, etc.) for sale that I could use for the swap. I assume that I could either swap the 89-95 complete vehicle wiring harness (front to rear) into the '82 and go with the original EFI or I could go the carb route and keep the original 4 cylinder under hood wiring. Am I correct with those being the two easiest or most logical options for wiring?

I know all about the rear end, suspension, brakes, etc. that I need to swap out, which is why I am going to buy a compete donor vehicle if I do this swap. I may go the aftermarket EFI solution once I decide on wiring options.
 

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Hey guys! First post in probably over a year and is finally about my cars!! I just picked up a minty 88 notch 2.3/5sp for cheap (of the 7 fox's I've had it is the nicest). I want to swap it badly as it's worthy of the time and energy needed to do it. I also have a 88 LX hatch 5.0/AOD (has an 89 MAF engine harness in it already).

Here is my main questions - I understand all the 5.0 wiring, brakes, fuel has to come over. I'm prepared for that.. where I couldn't find much discussion IS going from an auto to manual trans. I plan to use the 4cyl trans with a diesel ranger pilot bearing my main questions are -

1. I know I need to swap the AOD wiring for the 5sp wiring - my question is how? does it simply plug in?? Is the o2 wiring in with it?

2. Can I use the AOD ECU with the 5sp? I have heard that they can be used and the only difference is the auto ECU's do not retard timing during shifts like the manual ECU to drop RPM faster

3. I have an old Crane InterceptorII ECU tuner that works (currently plugged in the hatch) does anyone know if this has options for rewriting the ECU for the swap? I don't have a manual for it sadly, and it seems to just write over/ auto adjust perimeters of the stock ECU for a turbo/Nitrous setup.. plus allow custom on the fly tuning

Sorry if this was covered and I didn't see it, sad to say I have owned 7 fox's and all were 5.0/5sp car's except the current 2, and never done a swap..
 

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The transmission harnesses is separate, and it just plugs in. If you are keeping the 5spd, you don't need to swap it.

The O2 harness connects to the Main EEC harness over by the MAF. This is where mismatches occur and fry EEC's. If you take the main EEC harness, O2 harness, & EEC from your donor car you should be fine.
 
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Awesome thank you! I was worried I'd have to try to find another o2 harness! I was thinking I'd have to swap all the wiring from the 5.0 hatch to the notch, and the notch don't have A/C factory haha

So just plug the EEC 5.0 harness into the 4cyl's current wiring basically? (dash harness), and install the 5.0 cluster/EEC in the passenger side kick panel?
 
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