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CIS is made by Bosch and has been in use since the mid 70’s on Porsche Engines ,VWs and many other European cars. It stands for Continuous Injection System, which means that fuel is continually atomized into the intake manifold just upstream of the intake valve. Fuel flow is directly controlled by airflow through a mechanical connection to an air vane which in turn moves a plunger which regulates fuel flow. Pure CIS is altitude compensating to some extent, since when less air flows, less fuel flows. You could also dispense with carb heat since there is no venturi, and the primer since the cold start valve is built in. Decreased workload is always a good thing.
Electronically controlled systems
The fuel is supplied by an electrically driven fuel pump which develops the pressure necessary for injection. The fuel is injected by solenoid-operated fuel-injection valves into the cylinder intake ports. The injection valves are controlled by an electronic control unit (ECU) and the amount of fuel injected depends upon the length of time that they stay open. By means of sensors, the ECU is provided with information about the operating conditions of the engine and about the ambient conditions around the vehicle. The basis for assessing the amount of fuel to be injected is the amount of air drawn in by the engine. The L-Jetronic is an electronically controlled fuel-injection system. In the case of the L-Jetronic, the amount of air drawn in by the engine is directly measured by an air-flow sensor.
I’m very familiar with the Bosch CIS System since I own a Porsche with one of the legends of all Porsche engines, the 2.7L S engine. I bought one of the used engines from GotEngines.com. I was so happy and impressed, you can see that I am now the chief writer for their blogs because I believe in this company. They did me right. That is GotEngines.com @ 1-877-268-0664. Call us for a good education on used engines so you end up with the engine that is in your best interests.





