What does the D-type L-type engine mean? Give a brief description of

D-type L-type engines are not classified according to the arrangement of engine cylinders, but according to the way of detecting and measuring air flow.

The D-type engine is equipped with an absolute pressure sensor in the intake pipeline. By detecting the vacuum degree in the pipeline, the intake air volume of the engine is measured according to the engine speed. Another engine intake measurement method is simpler. This engine is equipped with a more accurate air flow sensor directly in the intake pipe, which is an L-shaped engine. In contrast, the latter is not only simple in structure, but also high in measurement accuracy, so it has been widely used.