need help with 86gt mass air conversion

scrubb · Mar 30, 2011

My friend is selling his 86gt to me but it needs to be converted to mass air. Im not sure exactly what I need. I am trying to do it myself and not buy a kit. I know i need a harness and an A9P pcm. What else do i need? Can any one help me out? thanks.

Noobz347 · Mar 30, 2011

Mustang Mass Air Conversion «

My only question before you go through all the trouble... What is the necessity? Is there a specific reason why you need to convert?

scrubb · Mar 30, 2011

Yeah. to be honest Im not to good with cars but he said the speed density ( I think) was messed up. He brought it to a shop and they said it can be fixed or replaced with mass air and the guy at the shop suggest that mass air is the better way to go

jrichker · Mar 30, 2011

MASS air conversion instructions from Mustang Mass Air Conversion « 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.

A9L computers are 5 speed only
A9P computers are automatic, but will work with a 5 speed.

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, actually less work that swapping the wiring harness.
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.

Also see www.forfuelinjection.com for help with the harness parts RJM Injection Tech — Welcome, and connector pins, RJM Injection Tech — Welcome

scrubb · Mar 30, 2011

Cool thank you

Mustang5L5 · Mar 30, 2011

scrubb said:
Yeah. to be honest Im not to good with cars but he said the speed density ( I think) was messed up. He brought it to a shop and they said it can be fixed or replaced with mass air and the guy at the shop suggest that mass air is the better way to go

Sounds like He has no idea how to fox the car. Good chance converting to mass air may still have same issue since they two systems share 99% of the same sensors.

What are the symptoms exactly and have you run the check engine codes? 1986 mustangs do not have a check engine light...so no way to know if a major code is stored

scrubb · Mar 30, 2011

No I didnt check the codes he might have but I didn't. The car idles fine and runs fine then 5 to 10 min it would start to bog down that's the main problem

1987stangman · Mar 30, 2011

scrubb said:
No I didnt check the codes he might have but I didn't. The car idles fine and runs fine then 5 to 10 min it would start to bog down that's the main problem

Converting to MA is not going to solve an issue automaticly and if the car is stock why convert? The real issue needs to be uncovered before you decided to convert or finding the problem will just create more headache for you esp. if your just going to sell it.

jrichker · Mar 31, 2011

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 18-Mar-2011 to advise differences in code information for engine running and engine off codes.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

See Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems.

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

Noobz347 · Mar 31, 2011

Well I gotta tell ya... I'm a huge fan of the old speed density system. Were it more flexible in what you could do with it (i.e. easily reprogram to accomadate larger cams, heads, and other mods), I'd still be running it.

If you're not running modifications that REQUIRE you to convert, then don't convert. You won't gain any performance by going mass air. Just as a side note... if you ever had any intentions of running boost, well... speed density LOVES boost and personally, I see speed density as considerably easier to tune for boost than mass air so long as we're not talking about a great deal of other mods.

scrubb · Mar 31, 2011

jrichker

Thank you for that whole diagnosis and what to do I'll have to go give that a try and see what happens

scrubb · Mar 31, 2011

Noobz347

The car is bored over to a 347 I believe it's got bigger injectors and a bigger exaust manifold.

Noobz347 · Mar 31, 2011

The injectors are the problem. I personally, know of no way to tune speed density for different size injectors.

I have heard rumor that Quarterhorse is capable of tuning SD. TwEECer is also supposed to be compatible with the SD EEC but IMO, it's a quirky, and complicated PITA.

Never played with the Quarterhorse though so I have no info about it.

scrubb · Mar 31, 2011

Noobz347

So if I went to mass air would that change or fix the problem in anyway?

Noobz347 · Mar 31, 2011

If you are in fact, running over sized injectors (over 24 lb/hr) then I would say that converting to mass air will give you the most/simplest option(s) for getting it all tuned.

Before you go running out and buying parts though... you NEED to know what you have in the way of motor.

The car is bored over to a 347 I believe it's got bigger injectors and a bigger exaust manifold.

This doesn't add up. What I mean is: Who bothers with the cost of building a 347 complete with after market exhaust and stock cam, heads, intake, etc.

Find out unequivocally, what mods you have under the hood and THEN (and only then) we can talk about whether or not you need to convert.

scrubb · Apr 12, 2011

ok i figured out what is in the hood i got a
bore .030
rods pistons everything
cams values all that stuff
x pipe
and thats about it what else you need to know? the exact specifics?

Mustang5L5 · Apr 12, 2011

On the camshaft...yes. What is it?

Speed density doesn't like too many aftermarket camshafts
Speed density doesn't like larger injectors

So whoever built your car messed up. You need to convert to mass air.

You need three things.

A9L or A9P computer depending on trans ($100)
Mass air meters (either calibrated for injector size, or use a larger ford oem and get a custom tune) ($$varies)
Ist mass air harness kit (about $45)

stang&2Birds · Apr 12, 2011

Has the engine ever run properly after it was rebuilt?
Geez.

Start from the beginning, before you, or anyone else, starts ****ing up the engine and setup even more than it is.

jrichker · Apr 13, 2011

stang&2Birds said:
Has the engine ever run properly after it was rebuilt?
Geez.

Start from the beginning, before you, or anyone else, starts ****ing up the engine and setup even more than it is.

He's right go back and dump the codes. Fix any bad sensors or bad wiring. See how the car runs and make an exact determination of what it actually has and does not have. Then consider if you need to convert to mass air.

Mustang5L5 · Apr 13, 2011

If he's running an aftermarket camshaft and larger injectors on speed density, it may never run right without MA

Of course, without specifics, really hard to say.

need help with 86gt mass air conversion

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