The efficiency of the triple-acting catalyst is optimal if the engine operates in a narrow range of control stoichiometric values (stoichiometry - the science of weight ratios) composition of the air-fuel mixture, denoted by lambda = 1. In the following, the lambda criterion informs about the relationship between the actual value of the composition "air-fuel" mixture and stoichiometric. From this it can be established whether there is an excess of free oxygen in the exhaust gases, which indicates a lean mixture. The ceramic material of the lambda probe is permeable to oxygen ions at a temperature not lower than 300°C. The outer surface of the ceramic is in the exhaust gases, while the inside is the reference gas. The difference in the concentrations of oxygen ions forms a signal proportional to the oxygen content in the exhaust gases. In VU, this signal is used to change the injection duration so that the mixture ratio fluctuates relentlessly around lambda = 1 (0,98–1,02). Manually adjust the CO content (carbon monoxide) impossible. Lambda probe (oxygen probe) located in the exhaust pipe close to the catalyst. After starting the engine, the lambda probe quickly warms up and enters into operation. In the absence of a signal from the lambda probe until it is connected, the control unit operates with simulated values. Own diagnostics checks the electrical part of the lambda probe, whether the signal has the appropriate values, or whether the lambda control is within the specified parameters.
Additional signals
In addition to information from sensors and information transmitted from actuators, the control unit also generates so-called additional signals. They are information received from other vehicle control units.