KJetronic

KJetronic, also known as Continuous Injection (CI) or simply "Jetronic," is a mechanical fuel injection system developed by Bosch. It was a significant advancement in automotive engine management, offering improvements in fuel efficiency and emissions control compared to carburetors. Introduced in the late 1970s, KJetronic was widely adopted by European automakers, particularly Volkswagen, Audi, Mercedes-Benz, and Porsche, throughout the 1980s and into the early 1990s.

The system operates on the principle of continuously injecting fuel into the intake manifold, upstream of the intake valves. A key component is the airflow sensor, a plate that measures the volume of air entering the engine. This measurement is translated into a mechanical pressure signal that controls the amount of fuel injected by the fuel distributor. The fuel distributor is a complex unit containing metering slits and plungers that precisely regulate fuel flow to each injector based on the air intake and engine speed.

Unlike later electronic fuel injection systems, KJetronic relies on purely mechanical and hydraulic principles. There is no electronic control unit (ECU) processing data and making adjustments. This mechanical nature contributes to its robustness and reliability, though it also means it lacks the fine-tuning capabilities of electronic systems. Despite its eventual replacement by more sophisticated electronic systems, KJetronic played a crucial role in the transition towards more efficient and cleaner internal combustion engines.