•  For vehicles with a diesel particulate filter system two post injections are employed during the regeneration process, in addition to pilot and main injections, depending on the requirements.

•  Advanced post injection is initiated in certain load/speed ranges immediately after main injection. Fuel is then injected during the ongoing combustion.

•  The main purpose of this advanced post injection is to raise the exhaust gas temperature during the regeneration process of the diesel particulate filter. In addition, some of the diesel particulates produced during regeneration are after-burned.

•  Retarded post injection only occurs shortly before bottom dead centre and also serves to raise the exhaust gas temperature.

•  In contrast to the previous injections, during retarded post injection the fuel is not burnt, but evaporates due to the residual heat in the exhaust gas. This exhaust/fuel mixture is delivered to the exhaust system by the exhaust stroke.

•  In the oxidation catalytic converter, the fuel vapor reacts with the residual oxygen (above a certain temperature) and burns. This provides sustained heating of the oxidation catalytic converter, which supports the regeneration of the diesel particulate filter.

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