Jetronic is a trade name of a manifold injection technology for automotive petrol engines, developed and marketed by Robert Bosch GmbH from the 1960s onwards.
D-Jetronic was essentially a further refinement of the Electrojector fuel delivery system developed by the Bendix Corporation in the late 1950s.
As in the Electrojector system, D-Jetronic used analogue circuitry, with no microprocessor nor digital logic, the ECU used about 25 transistors to perform all of the processing.
Two important factors that led to the ultimate failure of the Electrojector system: the use of paper-wrapped capacitors unsuited to heat-cycling and amplitude modulation (tv/ham radio) signals to control the injectors were superseded.
A variant of K-Jetronic with closed-loop lambda control, also named Ku-Jetronic, the letter u denominating USA.
L-Jetronic was often called Air-Flow Controlled (AFC) injection to further separate it from the pressure-controlled D-Jetronic — with the 'L' in its name derived from German: luft, meaning 'air'.
L-Jetronic used custom-designed integrated circuits, resulting in a simpler and more reliable engine control unit (ECU) than the D-Jetronic's.
Licensing some of Bosch's L-Jetronic concepts and technologies, Lucas, Hitachi Automotive Products, NipponDenso, and others produced similar fuel injection systems for Asian car manufacturers.
L-Jetronic manufactured under license by Japan Electronic Control Systems was fitted to the 1980 Kawasaki Z1000-H1, the world's first production fuel injected motorcycle.
LE3 (1989–), featuring miniaturised ECU with hybrid technology, integrated into the junction box of the mass airflow meter.
The 'LH' stands for German: "Luftmasse-Hitzdraht" - the hotwire anemometer technology used to determine the mass of air into the engine.
LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features; including fuel enrichment based on exhaust gas temperature (ex.
Mono-Jetronic is different from all other known single-point systems, in that it only relies on a throttle position sensor for judging the engine load.
The ECU uses an Intel 8051 microcontroller, usually with 16 KB of programme memory and without advanced on-board diagnostics (OBD-II became a requirement in model-year 1996.)