CIS stands for Continuous Injection System and the fuel "distributor" distributes fuel to each cylinder, but it it continuous, not timed. The German work for continuous begins with a "K", like compressor/kompressor.

The fuel flow is actually not purely continuous as the injector valves are designed to "dither" rapidly when sufficient pressure is available to overcome static seating pressure, and this "dithering" feature improves fuel atomization.

The CIS system is conceptually similar to the vintage Rochester Fuel Injection systems used on fifties/sixties vintage Corvettes and some other GM models, but the Rochester system is a little simpler. A pump driven by a cable off the distributor generates fuel pressure that is approximately proportional to engine revs. A spill valve that bypasses excess fuel is driven by a vacuum signal from a venturi on the air meter, and the linkage is designed so pressure to the injectors is proportional to air flow. The injectors do not have valves to overcome, and actual delivery pressure ranges from near zero to about 200 psi.

The CIS system's basic metering device is a "momentum plate" that can sense actual mass flow, so it self corrects for altitude to some degree. Movement of the momentum plate, which is usually referred to as an air valve operates the equivalent of a spill valve, and rather than fuel pressure being a function of engine speed, the CIS system uses an electric pump and regulator to maintain constant inlet pressure. Then the momemtum plate provides a basic setting for the spill valve, which is fine tuned by the EHA driven by the electonics, which uses engine temperature, ambient pressure (for more refined altitude correction) and O2 sensor output to drive the EHA correction signal.

The CIS-E is a nice system, but very complicated as it is a complete mechanical system and also has nearly all the elements of an EFI system.

Duke