The article presents results of a spark ignition engine examination, which has been conducted to establish the influence of exhaust gases recirculation on the engine performance and the toxic content in exhaust gases. The research concentrated on identifying a range of recirculation levels, which enabled to eliminate its negative influence on the engine performance by means of selecting an appropriate angle of advance. Further, the article discusses the engine examination procedures involving different recirculation control algorithms in the ECM chip. Finally, the article presents EURO II and EURO III tests, conducted on a vehicle/engine controlled by the above-mentioned software.