EFI parts question

VAFOX · Dec 28, 2011

I am slowly gathering parts to convert my 88' from carb back to EFI. So far I have an A9L computer and harness ($50 for both is good, right?). The motor is unknown as to the internals, but is believed to have a mild cam and has GT40p heads, ford racing headers into off-road mac exhaust. I plan to get GT40 intake, but would like to get opinions on the following:

what size fuel injectors (19# or 24# or other)
what size throttle body
anything else that will need to be geared toward the specific build?

Any suggestions on what parts to get, where to get them, and/or other items to note on the swap would be appreciated. Like I mentioned, this is going to be a slow process of collecting the necessary parts. I just want to be sure I am getting the correct stuff and all of the stuff. Any pictures of a swap or how the wiring is run or other tricks would be great too.

This is a budget swap. Any parts not to skimp on or anything that should be purchased new?

Thanks!

stdyhand · Dec 28, 2011

The 19lb injectors were stock, so unless your planning to get a tune your better off going with them. From the build you describe, it doesn't sound like you'll need anything larger than stock anyhow. Now if you are getting a tune, I'd go larger than 24's. It will leave you room to grow later. If you go with 19's, you can probably find a OEM MAF to match the 19's fairly cheap.

VAFOX · Dec 28, 2011

Should I purchase all new sensors or is used okay?

As far as injectors and tuning, I could get it tuned. At this point I would really like for it to be EFI again. Is it a lot cheaper to go with the stock setup, or would it be worth while to upgrade now? Is there great potential with going to larger injectors and maf with an almost stock setup?

need4spd90 · Dec 28, 2011

What year is the computer harness from? Only 87-89 will work with your existing 1988 dash/body harnesses...and only 1989(or a 1988 California) was mass air...

VAFOX · Dec 28, 2011

computer and harness are from a 92'

I can't make that work?

ID89GT · Dec 28, 2011

Not plug and play. I would look for an 89 harness

need4spd90 · Dec 28, 2011

VAFOX said:
computer and harness are from a 92'

I can't make that work?

Nope...plus you'll have 2 fuel pump relays if it's a late 92 harness lol...
Also beware of the oxygen sensor harness wiring..the wrong one WILL fry the trace on PIN 46 of your computer..been there, done that...

jrichker · Dec 28, 2011

You can make almost any 86-93 5.0 EFI Mustang harness work. The key thing is how much effort and electrical talent you need to put into it. As mentioned th 89 harness is a plug and play deal in an 87-88 5.0 Mustang. Others may take some work.

Copied from bbunt302
Just for reference, here's a list of all the compatible years:

89 harness should work for 86-89 as long as you're using mass air.
90 harness will only work in a 90. (because of air bags and dual dash connectors)
91 through early 92 harnesses should be compatible (single dash connector, fuel pump relay under driver's seat)
Late 92 through 93 harnesses should be compatible (single dash connector, fuel pump relay under the hood)

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 http://www.kustomz.com/cat3.html 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.

Also see www.forfuelinjection.com for help with the harness parts http://rjminjectiontech.com/?p=10, and connector pins, http://rjminjectiontech.com/?p=11

O2 Sensor harness interchange and modification
Originally Posted by 302EFI
Revised 16-Oct-2011 to add O2 sensor harness warnings
The wires for the 02's and low oil did not change throughout the years, they are all in the same place.
The main ones you need to worry about are (on the harness end (ECU) that plugs into the 02 plug) is:
\- 1. Lightblue / yellow
- 2. White / Purple
- 3. Purple / Yellow
The White/Purple & Purple/Yellow gets looped for a automatic ECU
The Purple/Yellow & Lightblue/Yellow for a manual ECU

See http://forums.corral.net/forums/general-mustang-tech/1094179-oxygen-sensor-harnesses-manual-auto-differences-year-differences.html for more O2 sensor wiring harness info
Basic premise to use with transmission swaps:
Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the computer internal signal ground.
90 model year harness only works with 90 model cars without inspection/rework.
The 4 cylinder O2 harness uses 4 wire O2 sensors. It probably won’t work correctly without modifying it.

need4spd90 · Dec 28, 2011

Trying to rewire an entire engine harness is way more headache than its worth..alot of times you can find someone to trade for the one you need, or just buy one then sell yours for the same price...

The fool proof method of test the o2 sensor harness compatibility is:
Remove the computer
Clutch down or auto in park
DVOM on pin 46 of the EEC connector and ground
Crank the engine using the key
Voltage on pin 46 while cranking, o2 harness is wrong..

No voltage, slam the EEC back in and go do a burnout

VAFOX · Dec 28, 2011

I want to make this as easy as possible, so I will keep my eyes out for an 89 harness. Good thing is that I am in no rush. It's running good with the carb and I plan to slowly collect parts and read up to find out more information on the swap.

Thanks for all the info guys. If anyone thinks of anything else worthy for me to know, please share. I've never tackled this kind of job before, so I'm a bit intimidated which is why I am going about this very slowly.

stdyhand · Dec 29, 2011

If it were me I'd make the harness work since that is what I would already have on hand and I am kind of cheap like that . I like to save money and put that elsewhere. But getting another harness would be the easiest route and you might be able to sell the harness you got now to make up for some of the money you spend getting another. It seems like I am always seeing people on these forums looking for a wiring harness so I don't think it will take long for it to sell.

Good luck with your project and don't get too discouraged. From the knowledge I've seen on this forum you should be able to get it running trouble free. I've been on several other mustang forums and this one by far has been the most helpful with regard to technical issues I've had.

vristang · Dec 29, 2011

I've rewired my 2.3 daily driver several times now, using the stock harness.
There were no 'drop in' harnesses available for what I wanted, so it had to be made...

Just get wiring diagrams for what you are starting with, and compare them to what you want to end up with.
Takes some time and it can get frustrating, but it can be worth it.
Depends on the owner I guess though...

VAFOX · Dec 29, 2011

Will I need to make any fuel line or setup changes?

VAFOX · Dec 29, 2011

Does anyone know how to identify each type of harness? There is a local harness for sale, but the guy doesn't know what year it came off of.

Any opinions on the "mass air conversion plug" used on 86-88 harnesses? They're on ebay for like $40.

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