Effects of ignition and injection timing on cold start behavior of methanol engine

The firing behavior of a 125 mL single cylinder methanol engine with electronically controlled injection spark-ignition at cold start was investigated experimentally. The effects of the injection timing and the ignition timing of methanol on the firing behavior and HC emission of the engine were studied by means of the cycle-by-cycle control technique. The results show that retarding the ignition timing from -20(before top dead center) to 10, results in more after-burning and the decrease in cylinder pressure gradually, and finally the engine fails to start. The optimal methanol engine ignition timing is -20. If the fuel injection timing is controlled reasonably during the engine cold start, it is possible to ensure the most fuel-air mixture to enter into the cylinder on time, leading to next cycle combustion after fuel injection and high cold start reliability. The maximum cylinder pressure increases by 140% and HC emission decreases by 65% when the methanol injection timing changes from -35 to 471 (after top dead center, crank angle).