The box you see here is a 1984 D.C. Johnson FAC-3 designed to retrofit the European market version of the 1984 and 1985 Porsche 928. These cars were equipped with a Hotwire Mass Airflow Electronic Fuel Injection System known as LH Jetronic.
The D.C. Johnson FAC-3 is an Air/Fuel control unit that adds the closed loop Oxygen sensor feedback loop to Electronic Fuel Injection Systems not originally equipped with this feature. It was designed to retrofit cars built for sale in the European market before emissions regulations were instituted, to meet United States specifications after they were imported into the United States of America.
ENGINEER”S NOTE: One of my “Hobbies” is upkeep of the legacy of this product line created by my Father David C. Johnson. These devices were produced from 1981 through 1986. The company that marketed them (D.C. Johnson and Associates Inc.) was founded in late 1982 and was closed in August 1986. I created the website dc-johnson.com in 2008 after an inquiry into the availability of technical information. This led to the realization that there was an ongoing interest in maintaining theses products and the cars on which they are installed.
Vernon Johnson May 15, 2014.