Exhaust gas recirculation function

As a result of exhaust gas recirculation, up to 40 % of the exhaust gases are directed back into the intake tract in the part-load mode. This lowers the oxygen content, the combustion rate, the peak temperature in the flame front and the emission of oxides of nitrogen without significantly increasing the soot emission.

The CDI control module (N3/9) controls the appropriate quantity of exhaust gases which are recirculated for the particular operating state by means of the air mass, on the basis of the input signal supplied by the hot film mass air flow sensor (B2/5).

Exhaust gas recirculation is performed on the basis of the map stored in the CR control module (N3/9) as soon as the following conditions are met:

 Idle speed: approx. 40 s temperature-independent afterrunning

 Part load

 Battery voltage 11-14 V

 Coolant temperature > 60°C

 Engine speed >1000 rpm

The EGR vacuum transducer (Y31/1) is actuated at the ground side and controls the vacuum to the EGR valve (101).