Dongfeng Xiaokang c37 engine dithered and emitted black smoke.

There are many cases where cars emit black smoke; The first mixture is too rich, resulting in incomplete combustion of the mixture, and the gap between the electrodes of the second spark plug is too small or too large, resulting in too small ignition energy and insufficient combustion of the mixture. Third, the gasoline you use is of low quality or model, such as 90 # gasoline. The fourth injector leaks oil, which leads to rich mixture, insufficient combustion and black smoke. At present, in the EFI vehicle, as long as the sensor is damaged in the electronic closed-loop control, the mixed gas will be too rich. For example, if the oxygen sensor at the end of the three-way catalyst fails, the computer will think that the mixture is too thin, which will increase the fuel supply and lead to black smoke in the final exhaust.