The map KFLBTS which specifies lambda values as a function of engine speed and cylinder charge controls enrichment of target lambda. This only activates when several variables which represent modelled temperatures (a) at the exhaust manifold, (b) in the catalytic converter, (c) near the catalytic converter (d) at the cylinder head or (e) near the lambda probe, in a sub-function LAMBTSENABLE have exceeded their threshold and a start-up delay time has expired. Apart from the cylinder head temperature which is 200°C, these values are typically 900-950°C.
Enrichment can be deployed in desired areas, attenuated or eliminated by means of the map KFFDLBTS (Kennfeld für Faktor Delta Lambdasoll für Bauteileschutz, map for the multiplication factor for the change in target lambda for component protection) with units (x,y,z): RPM, % load, multiplication factor.
In addition to LAMBTS, the ATR module controls the general enrichment at high load and speed (full load enrichment). EGT control is applied only if the controlled enrichment is insufficient which improves fuel economy. Unlike LAMBTS which uses modeled temperatures, ATR takes an actual temperature input from the EGT sensor. The set point for EGT regulation in the ATR function is given by constant TABGSS (Sollwert Abgastemperatur für Abgastemperaturregelung).