Lambda Oxygen Sensor
    (voltage measurement)

bk simmerath

Function

These curves in the diagram could have been taken from a real exhaust-gas testing session. Instead, the different pictures are simulations of the registered lambda sensor tension, oscillating around 0.5 V, for idle-speed, high number of revolutions with and without extra, disturbing air.

How it works

During cold idle-speed (see picture number 1) the lambda sensor is not working. The picture just shows the comparator voltage of the control unit (approximately 0.45 V). Picture number 2 displays the typical idle-speed slow oscillating movements. An analogue multimeter would show the same picture. With increasing number of revolutions, the movement intensifies (see picture number 3). In order to test the reaction time of the entire system, similar to the compulsory exhaust gas testing, extra air is put into the system at idle-speed (see picture number 4). The sensor tension remains for a moment at a tension that is correspondent to a mixture with relatively little fuel. Then, the control unit demands more fuel for the fuel injectors to compensate for the extra air. The same effect is present in picture number 5, only faster.