What is this thing? "FAC-2 Fuel Control Unit for Porsche Carrera"

[sroakley]

This "thing" was on top of my DME computer, it's labeled:
"FAC-2 Fuel Control Unit for Porsche Carrera" made by DC Johnson and Associates, Laguna Beach, CA.

It's about 3.5"x4.5"x1.5", gray colored and has a bunch of wires coming out of it, but none were attached.

My car is a 1984 911 Euro-gray market, with non-O2 sensor DME computer, but a catalytic convertor with O2 attached. I've owned it for a month, and I'm struggling with CA smog laws.

My ideas are that it's a device:

1. To enhance fuel delivery/fuel pump peformance
2. Interface the add-on O2 sensor with the non-O2 sensor DME computer.

Anyone know?

[ChrisBennet]

The DME's were the same internally. You shouldn't need anything extra to use the O2 sensor. Jumpers on the wiring harness make the difference and possibly a chip.
-Chris

[Joeaksa]

Where do the wires from the unit go and are they unplugged or cut or what? Did they have a plug on the end or connectors or what?

I have seen some people rig up a device to adjust their mixture from the interior but does not sound like this box is being used for this.

Joe

[sroakley]

The wires from the unit are disconnected. A couple wires have connectors, but most seem to be cut wires.

???

Steve

[MBAtarga]

If you can find a translator to decipher this document , it was the first link that showed up when I did a Yahoo search on

FAC-2 Fuel Control Unit DC Johnson

. Looks like a German Patent Office document.

[Steve W]

A quick read over the German document says something about the device being used for EPA federalization of European vehicles by using some type of variable resistance in relation to possibly the O2 sensor.

[TBuktu]

the document concernes only patent stuff

the additional johnson unit modifies input values so that the dme is getting ´false´ values from the sensors

so the regulation loop from the dme management can be influenzed

Tim

[Speedster94]

hallo
The Document says that johnson entered a Lawsuit against Guttmann . The reason is patent stuff but it is because of the Unit
on the Dme and the Cat .
I would say that the Device you have is some sort of control unit for the Lambdasensor and Fuel regulation .
If you have a chance get around the Cat stuff as it will choke your Car .
harald

[johnnyo200]

I have the same model car as you, mine didn't come with anything that you have desribed. But it also didn't come with a cat/O2 sensor for that matter. Wish I could help.

[sroakley]

Thanks for your comments and suggestions. It's a big help.

-Steve