[javadog]

K-Jetronic is the Bosch name for the system and CIS is acronym that is commonly used to describe it, as it injects fuel continously, rather than intermittently, like electronic fuel injection. It is a mechanical system, as opposed to an electronic system like Bosch Motronic. The injectors in a CIS system flow fuel all the time. In a typical electronic system, the injectors are opened and closed by electrical signals. The basic CIS design relies upon fuel pressure changes to regulate the mixture, as Randy stated.

In broad terms, there are a couple versions of the system. There are basic systems and systems with O2 sensor feedback. In the basic system, Bosch has sized all of the components in such a way for each different engine to give a particular engine the correct fuel mixture (or, close enough) at all times, provided the system is working correctly. The later systems have a computer of sorts that uses various means of altering the fuel pressure to affect changes in the fuel mixture, in response to feedback from the O2 sensor measuring the results of combustion. Within these two groups, there are many small variations. So, really, no two systems are truly identical. They pretty much made changes on a yearly basis, to correct little problems that were uncovered during real world use of the system.

As to your car, it would have originally has a 930/16 type engine, which used the version of CIS with an O2 system. You should have a computer, as the sensor will not accomplish anything without one. It sounds as if whoever installed the engine didn't correctly finish the job. If you want to continue running the cat, I suggest you give the car to a shop that is knowledgeable and let them sort out the details. Without a functioning O2 system, if you run the engine too rich you can destroy the cat. I've seen them actually get so hot they catch fire, which is not a pretty sight.

JR