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Engine management

The modern electronic engine management by BMW Motorrad ensures silky smooth running, an optimum torque curve, outstanding cold start ability and superb power delivery. It permits compliance with increasingly rigorous exhaust gas regulations and is required for the smooth running of the closed-loop catalytic converter. In addition the electronic engine management improves operating comfort, increases efficiency and provides numerous diagnosis facilities so that repairs can be carried out better, faster and at lower cost.

A key function of engine management is performed by the central control unit, which contains a high-performance microchip. This component calculates the optimum fuel injection quantity taking into account relevant operating parameters, the ideal fuel injection timing as well as the optimum ignition timing. To do so the control unit processes a large number of input signals provided by sensors. These include inductive sensors on the crankshaft and camshaft, which identify the engine speed and the current position of the crankshaft, together with the throttle valve sensor, which measures the opening angle of the throttle valve. The central unit uses these parameters to calculate the volume of air intake and the appropriate quantity of fuel to be injected. Other sensors for engine and outside air temperatures as well as air pressure also provide signals to aid fine tuning.

Finally, an oxygen sensor in the exhaust system provides information on the current fuel/air mixture composition. Exhaust gas components such as hydrocarbons, carbon monoxide and nitrogen oxide which are produced during combustion are minimised when the air fuel mixture is available in the ideal ratio of 14.7 to 1. This mix proportion is referred to as lambda = 1. Effective lambda regulation thus already prevents the generation of pollutants during combustion. The new flat twin boxer engine even has two of these lambda or oxygen sensors - one for each cylinder. In this way the mixtures for each cylinder can be inputed separately. This leads to exemplary emissions combined with reduced fuel consumption. In addition the new boxer engine features dual ignition. The ignition timing of each to the two spark plugs in each cylinder is freely programmed depending on the engine load and the engine speed. This so-called phase shift optimises refinement, exhaust emissions and fuel consumption.

The control unit has multi-dimensional grids stored within it which provide information on optimum ignition timing, injection and regulation of the other actuators. The engine management system also controls the cold start behaviour with electronically regulated engine speed control. This means that the engine always starts reliably - in every temperature and operating condition, whether cold or warm, on the flat or in the mountains. There is thus no need for a choke as a manual start facility.

With the launch of the new flat twin and four-cylinder engines, BMW Motorrad's leading position in the field of electronic engine management is further extended. For the first time, "BMW Engine Management" (BMS-K) is used here: a digital engine management system which has been specially developed for motorcycle requirements. Its control unit receives more input signals than was previously the case due to a considerably more extensive network of sensors. It compares this current engine data with the stored target figures, and fuel injection and ignition timing for each cylinder are optimised, resulting in impressive torque delivery and a much more finely tuned engine response. Data exchange between the control units, sensors and power consumers is effected by means of CAN bus technology. The conventional safety fuses are no longer required using this technology. They are replaced by special safety functions in the control units, work more precisely and do away with the need to change fuses.

At the same time, the new engine generation of both the new flat twin and the transverse inline engine also have a knock control system - installed in this way in a motorcycle for the first time. This system has sensors which identify uncontrolled combustion in each cylinder, with the electronic management system then adjusting ignition timing accordingly, thus avoiding possible damage due to the fuel having a lower octane rating for example. As a result, the flat twin engine designed for use with premium fuel can also be run on fuels of lesser quality, that might commonly be available in distant countries.

A BMS-K integrated electronic immobiliser ensures optimum anti-theft protection. A transponder in the key communicates with the control unit of the electronic engine management via a ring aerial in the ignition lock. This technology is currently the best and safest immobiliser system. The BMW Engine Management thus provides maximum reliability and operational safety in all conditions.