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This paper presents an experimental study on a 2-stroke SI engine, used on small portable tools for gardening or agriculture, aimed to identify possible correlations between parameters related to ionization current and air/fuel mixture richness, considering different fuels and spark plug wear. This, to realize a simple system to control the engine parameters and adapt them to engine aging and fuel type changing. The engine was fed with commercial gasoline, low octane number gasoline, alkylate gasoline and a blend of 80% gasoline and 20% ethanol. In all tests carried out with varying engine speed and spark advance the ionization signal was characterized by a single peak, resulting in the impossibility of distinguishing chemical and thermal ionization. All data collected were analyzed looking for correlations between all the available data of CO emissions and several characteristic parameters obtained from the ionization signal.

Increasingly stringent regulations in the field of pollutant are forcing engine manufacturers to adopt new solutions to contain exhaust emissions, such as Hybrid Electric Vehicles (HEV) or Full Electric Vehicles (FEV). Still far from the wide diffusion of FEV limited from electrochemical storage systems together with the difficulty of creating adequate infrastructure distributed throughout the territory to recharging batteries, the HEV seems to be actually a better solution. The hybrid vehicle is already able to guarantee satisfactory autonomy and low pollution levels by combining the advantages offered by the two technologies of thermal and electric propulsion. Currently on the market there are several types of hybrid vehicles, with different degree of hybridization (electric motor power versus propulsion total power), capacity to store electricity and type of scheme constructive adopted for the integration between the thermal engine and the electric machine.