What happened when Jianghuai M3 heard a bang after parking?

This may be due to noise caused by uneven engine cooling. Because the engine of the vehicle will have a very high temperature after driving for a period of time. Once the engine is turned off, the temperature of many parts on the vehicle will drop rapidly, but the proportion of thermal expansion and cold contraction of each part is different, so the metal parts will rub and then there will be a bang.

Another possibility is that the abnormal sound is from the exhaust pipe. After the vehicle runs, the temperature of the exhaust pipe will be very high, because there is mixed gas burning in the exhaust pipe, and it will expand when it is turned off and contract when it is turned off. The sound usually comes from the front end of the exhaust pipe and the soft joint.

Extension: 1. The spark plug loses its ignition ability. There is something wrong with the throttle valve. The above two problems will cause engine jitter and unstable speed. 3. Carbon deposition will cause insufficient combustion of gasoline, leading to engine jitter. The influence of engine carbon deposition on automobiles is considerable. First, the engine power is reduced, that is, the power output is uneven and gradually decays, in other words, it is getting less and less powerful. The second is to increase fuel consumption and increase your economic burden. Third, it is difficult to start a cold start, that is, it is difficult to strike a fire and it is not easy to get a taxi. Finally, serious carbon deposition in the combustion chamber will also lead to cylinder knocking, and low-speed acceleration will make noise, which will damage the piston and crankshaft, lead to engine heating, and seriously affect automobile safety. Then the discharge exceeds the standard, which not only fails the annual inspection, but also directly aggravates the harm of environmental pollution.