Engine Maintenance and Modification Bradley Artigue

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FIAT 124 Spider Engine Maintenance + Modification 5. Fuel Injection FIAT Spiders manufactured from 1967 through 1978 were equipped with carburetors. Vehicles manufactured from the 1980 model year through the end of production in 1985 were equipped with electronic fuel injection. There is some argument about the transition from carburetion to fuel injection. The most plausible story is that FIAT first offered fuel injection as an option, then as standard equipment in California, then as standard equipment for the entire line. Regardless of when or why you can always tell what system your vehicle had installed by looking at the body style number. This is the first four or five positions in your vehicle’s VIN number. The VIN is stamped in your engine compartment, on a small metal plate on your dashboard (near the driver’s side windshield), and on some models inside the driver’s side door. The first three positions will read “124” or (on later vehicles) “ZFA124”, followed by a two letter “primary” body code. AS, BS, CS1, CS2: CS0, DS: VX: Carburetion Fuel Injection Carburetion / Supercharger Fuel injection systems were provided by Bosch GmbH (“Bosch”). Carburetion and fuel injection approach mixing fuel and air in very different ways. Simply put, a carburetor mixes fuel outside of the combustion chamber. The mixture is drawn through a plenum into the combustion chamber. In a carburetor the settings that govern the mixture of fuel and air remain relatively static, fixed mechanically by the jets and orifices in the carburetor and when the vehicle is tuned. A fuel injection system sprays metered fuel directly into the manifold at the intake port during the intake cycle. The Bosch system used in a FIAT electronically controls the amount of fuel, resulting in more dynamic control of air to fuel ratios. By the end of the 1970’s fuel injection systems were slowly overtaking carburetion on the drawing boards of automotive engineers. Driven by emissions control regulations and a noticeable improvement in performance and fuel economy, fuel injection was evolving from complex mechanical systems to electronic “engine management” systems. The Bosch L-Jetronic system was used on the majority of European fuel injected cars, including FIAT, Alfa Romeo, Ferrari, Lamborghini, Lancia, BMW, Mercedes, Porsche, Renault, Volkswagen, and Peugeot. It was preceded by a number of mechanical systems, including the K-Jetronic by Bosch and mechanical systems by 38
FIAT 124 Spider Engine Maintenance + Modification SPICA, Kugelfischer, and others. Unlike its predecessors, L-Jetronic had an electronic brain controlling the injector pulse and numerous sensors telling the brain what the fuel system was doing. It is superseded by Bosch Motronic. Unlike Motronic, L-Jetronic is not as tightly integrated with the engine; one could consider L-Jetronic a “bolt-on” fuel injection system where Motronic is more “engineered in” to the engine design. Bosch has always been a leader in fuel injection worldwide because of its association with Mercedes and their leadership with diesel and aircraft engine design. Bosch began developing electronic fuel injection in the 1950s and licensed some early American designs as well. Bosch introduced electronic control to its production fuel injection designs in 1974. A more sophisticated and reliable system, the L-Jetronic soon emerged. An oxygen sensor followed and was quickly adopted by European car makers including FIAT who were struggling to make small high performance engines meet the 1980 California and 1981 U.S. Federal emissions requirements. 5.1 Fuel injection Basics Figure 33: Bosch L-Jetronic Fuel Injection as used in the FIAT Spider 2000. 39
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