An oil sump for a vertically shafted combustion engine has a housing with an upper face for sealing against a block of the engine. In one aspect, the host computer transmits a register update message to an ESL. For each injection pulse following the first one the respective start is selectively determined either as a time distance from the end of the immediately preceding injection pulse or as an angular distance from the relevant TDCC, in dependence on the instantaneous value of at least one predetermined parameter.