An ignition enhancer for a vehicle engine is installed between a conducting wire of a high voltage coil and a plug connector, provided with a capacitor, two conducting rods respectively extended outward from two ends of the capacitor, an insulation sleeve wrapping around the capacitor and filled with a waterproof resin to fully surround the capacitor, and two engaging grooves respectively formed in two ends of the insulation sleeve. Thus, with the conducting rods inserted in a core of the conducting wire of the high voltage coil and the plug connector respectively, the capacitor, storing an electric charge, is able to stabilize voltage and fulfill filtering to strengthen ignition power after starting a vehicle engine, not only advancing combustion efficiency to lower carbonization but also augmenting engine power.