MAF Conversion Help

If you want a true plug and play, you will need a harness out of an 89 mustang. Nothing else will work without modification. If you are going to leave the 88 harness and repin the connector and run new wires, I guess any 87-93 mass air connector would work.

MASS air conversion instructions from Mustang Mass Air Conversion | StangNet 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

If the idea of moving & soldering wires scares you, here's a list of compatible Mass Air wiring harnesses.

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. (B/c 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 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.

A Also see Ford Fuel Injection for help with the harness parts RJM Injection Tech EFI Harness Pigtails:, and connector pins, RJM Injection Tech Ford Terminals:

i bought a mass air kit from cpr and it was simple and came with connectors pins and prespliced wires

In my case, I wanted it to look factory, so I used an 89 harness. However, I can attest to the quote below. Even more fun to put it back in. IIRC, that was a 12 pack night with a lot of blood. If you go the 89 harness route, just wait until you think you're almost done and try to work the computer plug through the firewall and down to the computer.crapola Even more fun since I was doing the whole thing by myself in a small garage. Wiggle wires, walk around the car and squeeze myself between the garage wall and the car and reach up and see if I can grab the connector and if it will move. No.. Repeat..

jrichker said:

I have pulled the stock harness out of a wrecked car and it was like wrestling a big python.

Click to expand...

That being said, if you use a a9p in a stick car(or vice versa), you will have to repin a wire in the o2 harness connector under the mass air sensor. You will see a short wire that loops around and goes right back into the connector in the half of the harness that goes down to the o2 sensors. You will also see a blank in the connector. Move the looped wire one pin over and you will be good as long as it's an a9p into a stick car(This is my combo. IIRC, there is something different to do with an a9l in an auto car due to the way the automatic trans grounds the neutral sense wire) If I can, I'll find the link for you.

Here's what I was thinking about.. Hardcore 5.0 bbs has changed formats and my links no longer work.

Manual/Automatic EEC Code Wiring Differences

There is a hardware difference between an auto processor & a manual processor. The difference is because of the way the NDS [neutral drive switch, manual transmission] & the NSS [neutral safety switch, auto transmission] are wired. They are both wired to the same pin#30 but the auto trans wiring grounds the pin to the starter solenoid & the manual grounds to signal return, during crank mode there is a voltage spike sent to pin-30 so the auto trans processor has a diode on pin 30 where as the manual processor doesn't, most of the time this won't cause a problem unless you get into a prolonged crank condition.

Those that want to convert their automatics to manuals, and swap the ECM, need to clip the wire going to pin 30 or else the ECM will fry the trace off the board. This leaves the manual EEC unable to dump codes, which looks for the loop through the neutral sensing switch of the T5 transmission.

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I have a 90 auto with a harness and computer from a 90 5 speed. is this why I cant read codes. Is it fried or do I need to move a wire? Runs great.
Thanks ken

kb65 said:

I have a 90 auto with a harness and computer from a 90 5 speed. is this why I cant read codes. Is it fried or do I need to move a wire? Runs great.
Thanks ken

Click to expand...

Yes, this could be why you can't read codes. I believe you do need to move the wire, and as per the document I quoted, unless you get into an extended crank condition, you prob did not fry the trace. If you look under your mass air sensor, you will see the O2 harness connector. It is a round connector. You will see a short wire that loops around and a blank hole next to one side of it. It should be moved over one spot. I wish I could describe it better, but it will make sense when you look at the harness. Let me know.
It is connector #40 on this diagram, but not on the main harness side. You will see it on the o2 harness side.

what is different about the 89 vs the say 92 or 93 harnesses. also how hard would install be with the IST harness? I have the harness/computer for a 93, but at the time it was also going to go intoa 93 car. now I want to put it into an 87 what kind of difficulties would I run into?

Why can't we put a 1990 harness into an 89 car? plugs on the driverside firewall are the same - only thing the 1990 harness has is plugs for the airbag. If that circuit is seperate to itself, no reason a 1990 harness wouldn't work in theory right?

i used an a9p computer with my 5 spd-50$,94 gt mass air-35$, pigtail from junk yard just soldered longer wires on-free, ecu pins 15$,wire from radio shack for fuel relay-15$, vss sensor & cable 25$ {if you do not have cruise control} about 3 hours of my time- free.
about 140$ all together. just follow the instructions. dont spend 500$ for a kit thats easy enough to duplicate.
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