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Contemporary diesel engines are high-tech power plants that provide high torques at very good levels of efficiency. By means of modern injecting-systems such as Common-Rail Injection, combustion noise and emissions could be influenced positively as well. Diesel engine are therefore used increasingly in top-range and sports cars. Today's production ECUs have no or only very low feedback regarding the process in the combustion chamber. As long as this data is missing, the design of the maps in the ECU can only be a compromise, since production tolerances and aging processes have to be considered in advance. Disturbances in the combustion process may not be detected at all. If more knowledge about the course of combustion is provided, especially the start of combustion (SOC), various operating parameters, such as the pilot injection quantity or the beginning of current feed to the injector, could be adjusted more precisely and individually for every cylinder.

Regarding the strongly growing two-wheeler market fuel economy, price and emission legislations are in focus of current development work. Fuel economy as well as emissions can be improved by introduction of engine management systems (EMS). In order to provide the benefits of an EMS for low cost motorcycles, efforts are being made at BOSCH to reduce the costs of a port fuel injection (PFI) system. The present paper describes a method of how to reduce the number of sensors of a PFI system by the use of sophisticated software functions based on high-resolution engine speed evaluation. In order to improve the performance of a system working without a MAP-sensor (manifold air pressure sensor) an air charge feature (ACFn) based on engine speed is introduced. It is shown by an experiment that ACFn allows to detect and adapt changes in manifold air pressure. Cross-influences on ACFn are analyzed by simulations and engine test bench measurements.

Equipping low cost two-wheelers with engine management systems (EMS) enables not only a reduction of emissions but also an improvement in fuel consumption and system robustness. These benefits are accompanied by initially higher system costs compared to carburetor systems. Therefore, intelligent software solutions are developed by Bosch, which enable a reduction of the necessary sensors for a port fuel injection system (PFI) and furthermore provide new possibilities for combustion control. One example for these intelligent software solutions is a model based evaluation of the engine speed. By use of the information contained in the engine speed signal, characteristic features like air charge, indicated mean effective pressure (imep) and combustion phasing are derivable. The present paper illustrates how these features could be used to reduce the system costs and to improve fuel consumption and system robustness.