Mechanisms of combustion intensification in a syngas-air mixture supersonic flow behind the oblique shock wave front are investigated when the vibrations of reactant molecules are pre-excited. The simulation shows that the excitation of H2, N2, and CO molecules in front of the shock wave is much more effective to shorten the induction zone than mere heating the mixture. The energy efficiencies of both methods of combustion initiation are compared. It is shown that in order to ensure the identical ignition delay length it is needed to put noticeably greater specific energy in the case of heating the gas than that upon the excitation the molecule vibrations. In addition, low-temperature ignition of the mixture with vibrationally pre-excited H2, N2, and CO molecules makes it possible to raise the efficiency of conversion of the reactant chemical energy to the thermal energy released during combustion compared with the method of heating the mixture.