Similarities and differences between D-type and L-type intake control of automobile engines

Similarities: The purpose is the same, both of which are to calculate the air intake or charging efficiency of the engine. In addition, it usually helps to measure the intake air temperature to compensate the actual intake air volume. Through different calculation methods, ECU finally gives the charging efficiency at different speeds. This is the first step of engine bench calibration, and the subsequent fuel injection quantity is based on it.

Difference: The measuring principle is different. Generally, the L-type air mass flowmeter is adopted, and the hot-film or hot-wire air mass flowmeter with thermal compensation is widely used to directly measure the intake air volume, and the installation position is generally behind the air filter and before the throttle. But for many high-end engines, such as supercharged engines, a pressure sensor will be added behind the throttle to control the intake air more accurately. For example, Magotan EA888 is such an engine.

Type d uses an intake pipe pressure sensor. The principle is that at a certain temperature, the intake air flow is directly proportional to the subsequent air pressure. The installation position is behind the throttle. Finally, the inflation efficiency of the engine is obtained by using some calculation method of ECU.