Determination of the index values of the monitoring and diagnostics unit of the intake tract of a gasoline engine

Abstract

This paper discusses the research findings on the determination the index values of the monitoring and diagnostics unit of the gasoline engine air supply system integrated into the intake tract of the VAZ-21114 bench engine using the developed specialized equipment as well as the distribution of the dependencies of the leak area and the index of the analog-digital sensor signal. It was found that at atmospheric pressure in the intake manifold of the car, a sensor voltage of 4.135 V was observed, while at underpressure, the analog-to-digital sensor signal decreased. At normal underpressure in the intake tract of the car engine, it is observed that the analog-to-digital sensor signal is 1.15 V. With a leak of 0.78 mm², there is an abrupt voltage jump due to an abrupt depressurization of the intake tract and decreased air discharge pressure which, if there is a leak from 0.78 mm² to 7.06 mm² inclusive, is represented as a gradual increase in voltage. The drawn polynomial line, depending on the values on the graph, allows to accurately estimating the degree of signal change depending on the leak in the intake tract of the engine. With significant ranges of increase in the leak area, there is a gradual increase in the readings of the analog-to-digital pressure sensor signal, and if the intake manifold pressure discharge limit is exceeded, the engine transits to a state critically different from the nominal one. The range of deviations of the leak area has a small effect on the deviations of the discharge pressure due to the presence of depressurization of the air supply system to the car engine and the transition of the boundary values of the pressure discharge index at which the engine operates.