Starting and post-starting

Starting and post-starting

During start-up, engine phase cannot be identified and phased injection cannot therefore be implemented.

An initial simultaneous injection is carried out during the first few engine revolutions (full group) because the considerable fluctuations in rotation speed do not permit injection time to be calculated correctly. Only subsequently does injection becomes phased.

The base pulse constant is increased by a certain factor throughout the period when the engine is cranked by the starter motor.

Once start-up has taken place, the factor is gradually reduced to zero within a given time period, which is in inverse proportion to engine temperature.

k : enrichment factor
t : time
α : decrease proportional to engine temperature
ON: engine cranked
OFF: engine running

Cold operation

Under these conditions, the mixture becomes naturally leaner due to reduced evaporation and heavy fuel condensation on the intake manifold internal walls. The greater viscosity of the lubrication oil also brings about an increase in the rolling resistance of internal engine components which also serves to exacerbate matters.

The electronic control unit recognises this condition and corrects injection time on the basis of the coolant temperature signal.