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Jetronic is a trade name for a type of fuel injection technology marketed by Bosch from the 1960s forward. Bosch licensed the concept to many automobile manufacturers. There are several variations of the technology, which represent technological refinements as time passed.

[edit] D-Jetronic (1967-1976)

Analog fuel injection. The depression (vacuum) is measured using a pressure sensor located in the intake manifold, in order to calculate the injection time period for the fuel. Originally, this system was just called Jetronic, but the name D-Jetronic was later used to distinguish it from the newer versions. The 'D' stands for 'Druck', which is a German word meaning pressure.

[edit] K-Jetronic (1974-c.1988)

Mechanical fuel injection. The 'K' stands for Kontinuierlich, the German word for continuous. This is different from pulsed injection systems in that the fuel flows continuously from all injectors, whilst the fuel pump pressurises the fuel up to approximately 5 bar (72.5 psi). The air that is taken in is also weighted to determine the amount of fuel to inject. Commonly called 'CIS' (Continuous Injection System) in the USA. This system has no lambda loop or lambda control. K-Jetronic was installed into a number of VAG, Ferrari and Ford cars.

[edit] K-Jetronic (Lambda)

A variant of K-Jetronic with closed-loop lambda control. Was developed to comply with Californian exhaust emission regulations, and later replaced by KE-Jetronic.

[edit] KE-Jetronic (c.1985-1993)

Electronically controlled mechanical fuel injection. The ECU may be either analog or digital, and the system may or may not have closed-loop lambda control. Commonly known as 'CIS-E' in the USA. The later KE3 (CIS-E III) variant features knock sensing capabilities.

[edit] L-Jetronic (1974-c.1989)

Analog fuel injection. This system uses a vane-type Air Flow Meter (AFM). This type of air flow meter is called LMM, LuftMassenMesser, in all Bosch documentation. It had a much simpler and more reliable ECU than D-Jetronic, due to use of custom-designed integrated circuits. It was used heavily in 1980s-era European cars [1]. Similar systems have been built under license by Lucas, Hitachi Automotive Products, and Nippondenso. However, although their key components look similar to L-Jetronic parts, those systems should not be called L-Jetronic and parts are usually not compatible. The 'L' stands for 'Luft', which is a German word meaning air.

[edit] LE1-Jetronic, LE2-Jetronic, LE3-Jetronic (1981-c.1991)

This is a simplified and more modern variant of L-Jetronic. The ECU was much cheaper to produce due to more modern components, and was more standardised than the L-Jetronic ECUs. The connections between AFM and ECU are simplified. Three variants of LE-Jetronic exist: LE1, the initial version. LE2 (1984-), featured cold start functionality integrated in the ECU, which does not require the cold start injector and thermo time switch used by older systems. LE3 (1989-), featuring miniaturised ECU with hybrid technology, integrated into the junction box of the AFM.

[edit] LU-Jetronic (c.1983-c.1991)

The same as LE2-Jetronic, but with closed-loop lambda control. Initially designed for the US market.

[edit] LH Jetronic (1982-c.1998)

Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for Luftmasse-Hitzdraht - the hotwire anemometer technology used to judge air mass into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller and usually a 4 KB program memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 16 or 32 KB program memory. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features including electronic boost control and fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT engine). Some later (post-1995) versions contain hardware support for advanced diagnostics according to ISO 9141 (a.k.a. OBD-II). The 1995 and newer Volvo 940 vehicles are one such example.

[edit] Mono-Jetronic (c.1988-c.1995)

Digital fuel injection. This system features one centrally positioned injection nozzle. In the US, this kind of single-point injection was marketed as TBI (by GM) or CFI (by Ford). 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. There are no sensors for air flow or intake manifold vacuum. Mono-Jetronic always had adaptive closed-loop lambda control, and due to the simple engine load sensing, it is heavily dependent on the lambda sensor for correct functioning. The ECU uses an Intel 8051 microcontroller and usually 16 KB of program memory. Usually no advanced diagnostics.

[edit] See also

• Motronic

[edit] External links

• History of the D-Jetronic System
• Fuel Injection Theory