94/95 Holley Adapter Board - Development

SorsCode

Dirt-Old 20+Year Member
Jun 10, 2003
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St. Louis, MO
Since Holley makes the almost plug and play option for the Fox Body cars there really isn't anything for the 94/95 folks. For us we have the CCRM and remote TFI which can all be dealt with, but I decided to just make an adapter. The idea here is, you plug the adapter board directly into the EEC-IV connector, then run the pigtail to under the passenger seat location. Then plug the pigtail into the Holley. This would allow for the use of all the factory wiring, IAT and ECT sensors as well. Meaning you really only need the Holley ECU, a wide band oxygen sensor and main power harness.

Now this is a "Development" Board pictured below. The production board will have a header style connector on the other side versus soldering wires. The idea here is to make sure everything works as designed. The spots for transistors and resistors is to allow "like" function of the cooling fan and fuel pump. Holley's fuel pump trigger is 12v and Ford factory was a Ground. This board resolves that issue, and resolves the issue of the ECU grounding the low speed fan to keep it off. It will function just like the factory did. This also incorporates A/C functions as well.

It will require a "sub" harness that I'd include as well for the wide band oxygen sensor, along with fuel, oil and map sensors. Production version you will just plug that sub harness direction into the adapter board and away you go. Doing it this way also allows ALL gauges to function.

Anyways sorry for this being so long, but wanted to share. I don't mention which Holley EFI because the idea is, this will work with Terminator X, Terminator X Max, HP, and Dominator.

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Where do you plan on sourcing the EEC connectors from?
I have about 200 of them in a box. I was huge into Megasquirt years ago, so I'd de-solder them from PCBs out of older Fords and collect them. At one time I had close to 1k of them. I still have a large number of junk EECs that I can grab more connectors from. I don't see me running out unless something crazy happens.

I'm also in talks to having them reproduced.
 
That was my main issue when I was contemplating my own ms3pro kit for the fox. Fwiw I do alot of electronic development and circuitry including pcb design if you ever hit a roadblock.
Sweet! I’ll keep that in mind. I do a lot of this too but more as a hobby. I design a lot of microcontroller and automation stuff as well as immobilizers with 4G/LTE
 
Figured I would post an update. I have actually completed this. I was able to sit down, solder in the little components needed along with the wiring. I then did some bench testing to make sure the circuits worked correctly, then did some test driving with a CCRM on the bench. After that it was time to make the pigtail and sub harnesses. All in all this went really smooth and works really good. No removing or rewiring of the factory components. The factory IAT and ECT sensors stay, after looking at Holley's data for the Modular Ford sensors they matched the 87-95 IAT/ECT values. The sub-harness has provisions for an Oil Pressure, Fuel Pressure and Manifold Air Pressure sensor on it. The wideband I already had in the car so nothing special was needed there since I used the same one Holley uses, but if I produce a kit, that will be part of the sub-harness.

This unit is a beta unit, which is why I soldered the wires directly to the board. The new board that I have designed will have the header(s) on the opposite side of the ECU connector for the Sub-Harness, I/O Harness and Pigtail to connect to the Holley. I know a lot of people think this was a crazy idea because who wants to keep the factory wiring and I don't disagree the benefit of this is for the people who don't want to wire in relays for FANs, keep A/C, or afraid of wiring in general. Since it is 100% plug and play, it could be installed within an hour.

Let me know what you think.

For anyone that notices in one picture you will see another one of my PCB creations with an OBD2 connector on it. This is my troubleshooting harness, works similiar to the adapter for Holley, goes between the stock computer and factory wiring. Lets you back probe all the connections and also lets you use a tool like ForDiag to see Live Data directly from the EEC-IV.

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I purchased a terminator X max for 94 Gt and I am lost, its not as plug and play as I see it.
It is not, my setup turns it into Plug and Play.

To keep the CCRM in place, you need to convert the Terminator X's Fuel Pump trigger from a positive current to ground, I did this using a simple resistor and transistor combo, for the Low Speed fan, you'd have to build a circuit similar to mine, because it needs ground to turn the fan OFF not ON. High Speed will work no issue along with the A/C stuff.

This is why I designed the adapter above is to make this swap much easier for the everyday customer.
 
You don't necessarily have to reverse the fan with hardware... You just have to be able to create a software loop to reverse the output polarity.
Correct, one solution was to set the output to turn on at 0* and off at 221* then back on at 211* or below. This would also fix it, but the concept here was to replicate how the factory fan worked when the ECT was disconnected or bad and the fan would run.
 
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I know its been a while but wanted to put out an update.

I had to go back to the drawing board a little bit. The connector (Molex) that I planned on using and actually did use on a few test units did not meet my expectations. I worked with my parts supplier and we came up with a new solution and they sent me some samples. I have a small run of test boards being fabricated up and as soon as they are done I'll get them assembled. Here is the latest rending.

I have this setup to work with either an Automatic (AODE/4R70W) or manual transmissions. I've also designed a version for the 87-93 group. Once these move to the full production setup I'll start on finalizing my 96-98 4.6L 2v & 4v version. In early stages right now is the 99-04 4.6L 2v & 4v. The goal there is the ability to be able to remove the factory ECU but keep the gauge cluster functional. This part will take some time but nothing I haven't done on other platforms in the past.

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