The catalyst can work efficiently only when the relative amount of air λ (lambda) as close as possible to 1. To achieve this, the MPI/MPFI ignition/injection system is equipped with a so-called lambda control. In this case, the lambda probe measures the amount of oxygen in the exhaust gas - a comparative value for determining the composition of the fuel-air mixture. If the measured value deviates from the ideal, then the control unit carries out additional adjustment. The adjustment functions in the range from λ=0.8 to λ=1.2.
The lambda probe delivers a usable signal only at temperatures above 350°C. In order to quickly reach this temperature, the probe is heated electrically. Before the desired temperature is reached, the system is not regulated and is guided by a given average value λ.
Audi's six-cylinder all-wheel drive model has two catalytic converters and two lambda probes.
Visitor comments