Equations of State are important from the theoretical and experimental point of view and especially in the design and modeling of processes in the industry. A general methodology is proposed in this work to obtain precise vapor pressures representation of polar and nonpolar pure compounds and new mixing rules to improve the robustness of three parameters cubic equation of state to predict phase equilibria of mixtures. In this paper the Patel-Teja equation of state has been modified to improve its accuracy for pure compounds and mixtures. It was introduced a temperature dependence of the attraction term in order to reproduce accurately vapor pressure of 311 pure compounds containing alkanes, alcohols, refrigerant, and sulfur compounds with a error less than 1%. New mixing rules are proposed to improve the representation of vle equilibria and pvt properties of mixtures