In this paper, the semi-empirical model, formulated in the earlier paper [1], was used to control engine exhaust emission under steady-state conditions. The presented optimization method enables us to find the values of engine control parameters that lead to minimization of nitrogen oxide emission. Moreover, the presented method ensures proper engine operating parameters such as mean indicated pressure, thermal efficiency and maximum pressure in the cylinder. Results of numerical calculations are compared with experiment data. An acceptable accuracy was achieved.