Engine Converting mass air back to speed density

a50ina50 · May 20, 2023

I am considering converting my 1988 SSP back to factory speed density. A previous owner converted it to the mass air. The engine is completely stock. I don't plan on modifying iit. Has anyone changed their converted mass air mustang back to factory speed density? What is involved? I know I have to remove the mass air sensor and install a speed density intake tube, which I have.

Rdub6 · May 20, 2023

The ECU was most likely changed, along with some wiring to it, that would need to be reversed. I’m not sure if the mass air computer can be used for speed density. Is the car a manual or auto?

Do you know what computer is in it? (Behind the passenger side kick panel).

Noobz347 · May 20, 2023

Rdub6 said:
The ECU was most likely changed, along with some wiring to it, that would need to be reversed. I’m not sure if the mass air computer can be used for speed density. Is the car a manual or auto?

Do you know what computer is in it? (Behind the passenger side kick panel).

No, you cannot use a MAss Air EEC for SD.

a50ina50 said:
I'm not conducting a poll and looking for a bunch of opinions.
I am considering converting my 1988 SSP back to factory speed density. A previous owner converted it to the mass air. The engine is completely stock. I don't plan on modifying iit. Has anyone changed their converted mass air mustang back to factory speed density? What is involved? I know I have to remove the mass air sensor and install a speed density intake tube, which I have.

You need to determine how the conversion was done. Here's how I did mine... (I think):

MAF - Mustang Mass Air Conversion - StangNet - The Mustang Network

The Serious Enthusiasts Site for the Ford Mustang Lover. Promoting the Legend of the Ford Mustang. Photo Classifieds, News, 1000's of Mustang Pics in our Stable, Parts Review, Part Shopping, Forums, Links, Chat and more.

stangnet.com

There are other conversions that include an [adaptor] (these were popular for a time). If you have one of these, it just needs to be removed and plugged into an SD EEC.

rednotch · May 20, 2023

Depends how he did it, if its the old ford motorsports kit, hook the MAP sensor back up, and unplugging the adapter harness, then just bolt the SD computer to the original harness, done... If they hard wired it you need to undo that and depin the ecu connector to return it back to the way it was, may even need a harness if they swapped in an 89 one.

a50ina50 · May 20, 2023

Rdub6
My mustang is a 5 speed. I don't know which computer is in it currently. I haven't pulled it out.

CAMTWO1070 · May 20, 2023

You need a DA1 computer to go back to speed density....

You will also have to add a vacuum line to the bap sensor circuit aswell as repin the whole EEC plug if the mentioned converter plug isnt present which in essence eliminates the MAF and repins some others which isnt overly hard when you know how to remove the pins without damaging the plug....

On the EFI Dyno tuning page there is a pinout schematic for almost all of the EEC-IV computers including 1988 Speed density cars..

I hope this link is ok to post . A9L computers use a GUFB strategy.

ECU Pinouts / EFIDynoTuning

With a jewleres loupe you can see the lil levers that hold the pins in place with help of the red wedgelock that need to be gently pried to the side with a small jewelers screwdriver then gently pried back so the red wedgelock can do its job....

CAMTWO1070 · May 20, 2023

a50ina50 said:
I am considering converting my 1988 SSP back to factory speed density. A previous owner converted it to the mass air. The engine is completely stock. I don't plan on modifying iit. Has anyone changed their converted mass air mustang back to factory speed density? What is involved? I know I have to remove the mass air sensor and install a speed density intake tube, which I have.

If you have the vacuum line hooked up to the BAP along with the MAF being plugged in thats where your problems exist...

If you have the vac line hooked up you have a MAP with a MAF system instead of a BAP with a MAF.

A BAP sensor has no vacuum line and uses Barometric pressure instead of vacuum to send info back to the ECU by telling the ECU the elevation above sea level you are traveling/...

If you can Id post up a few pictures of how the MAF and BAP is installed in your car....

Mustang5L5 · May 21, 2023

How was the conversion done? That will kinda dictate how to undo it.

a50ina50 · May 21, 2023

a50ina50 · May 21, 2023

a50ina50 · May 21, 2023

I don't want to go ripping stuff out. Any chance these pictures help identify what I have?

Mustang5L5 · May 21, 2023

Not really. But you really only need to swap two pins and you can install the SD ecu

Do you have an ECU ready?

Are you looking to completely remove the MAF plug or are you willing to tuck it?

a50ina50 · May 21, 2023

Mustang5L5...I don't have an ecu yet. I planned on doing away with the wiring and possibly selling the mass air stuff.

Mustang5L5 · May 21, 2023

Here’s one of the better write-ups for going from speed density to mass air.

You’ll need to go the opposite route.

MAF - Mustang Mass Air Conversion - StangNet - The Mustang Network

The Serious Enthusiasts Site for the Ford Mustang Lover. Promoting the Legend of the Ford Mustang. Photo Classifieds, News, 1000's of Mustang Pics in our Stable, Parts Review, Part Shopping, Forums, Links, Chat and more.

stangnet.com

Section 4 is the only pin swaps needed. You’ll have to revert back.

Pin 19 fuel pump monitor can stay

The VSS pins can stay.

The MAF plug can just tuck away, or cut down at the ECU and tape up the loose ends.

Pull off the MAF sensor and tubing, and plug the MAP sensor back to direct manifold vacuum

a50ina50 · May 21, 2023

Mustang5L5....thank you very much. Any suggestion on where to buy an ecu from?

Mustang5L5 · May 21, 2023

5-spd or auto?

rockauto has a bunch. Seems less demand for SD computers. I would eat the core charge though as a mass air ECU is worth way more.

I think SSP cars did get a different ECU, but I don’t know how easy that will be to find.

rednotch · May 21, 2023

That's pretty clean swap, hard to tell what harness that is from those pics. I would fish it threw the firewall first after unbolting the ecu, see if it still has the tag on it or look at other parts of it to figure out if its a modified factory one or an 89 mass air harness they swapped in. I don't see any splices besides those two butt connectors.

Jarhead67 · May 27, 2023

a50ina50 said:
I am considering converting my 1988 SSP back to factory speed density. A previous owner converted it to the mass air. The engine is completely stock. I don't plan on modifying iit. Has anyone changed their converted mass air mustang back to factory speed density? What is involved? I know I have to remove the mass air sensor and install a speed density intake tube, which I have.

You’ll have to remove the mass air sensor, replace the ECU with a speed density ECU (I have one), either replace the harness with a stock one or re-pin the one you have, and connect the BAP as a MAP.

Jarhead67 · May 27, 2023

Rdub6 said:
The ECU was most likely changed, along with some wiring to it, that would need to be reversed. I’m not sure if the mass air computer can be used for speed density. Is the car a manual or auto?

Do you know what computer is in it? (Behind the passenger side kick panel).

Mass air ECU cannot be used on speed density

Willybill32 · May 28, 2023

I have to ask the question: why would you want to go back? I upgraded my '86 to mass air with a Ford kit. I drove it that way for a long time and it worked great. Since then, adding heads, cam, etc., the mass air handled everything with no issues.

Bill

Engine Converting mass air back to speed density

Member

So while I wait to figure out my rear end issues

Stangnet Facilities Maint Tech... Er... Janitor

I'd like to remain having one chocolate starfish

Member

Active Member

Active Member

That is…until I whipped out my Bissell

Member

Member

Member

That is…until I whipped out my Bissell

Member

That is…until I whipped out my Bissell

Member

That is…until I whipped out my Bissell

I'd like to remain having one chocolate starfish

But at least it's tight!

Similar threads

Privacy & Transparency

Privacy & Transparency