Method of setting up an inversion diagnostic for number of lambda probes in internal combustion engine to determine correlations between banks of cylinders, mountings and lambda probes

摘要

At least one exhaust gas line (2) with at least one lambda probe (6, 7, 8) is connected to each inlet of an engine management system. During an interval, engine operation is monitored while the supply under pressure to at least one bank of cylinders is cut. The resulting lambda signals are sampled to determine the correlations between banks of cylinders, mountings and lambda probes : The correlation is determined from evaluation of the time offset of indication of an exhaust gas rich in oxygen by at least two lambda probes after stopping the supply under pressure. In the case of an engine with only one bank of cylinders, a control is effected by following a preset logic indicating exhaust gases rich in oxygen after cutting the supply under pressure. In the case of an engine with at least two banks of cylinders, the time offset TB of starting the cutting of supply under pressure is foreseen for each bank of cylinders. Control is carried out following a preset logic for each cylinder bank. TB is at least greater than the sum of the propagation time of gases in the exhaust gas line between the engine and the lambda probes, and the time for oxygen to pass through the catalyst system, preferably the precatalyser and/or the main catalyser. For each bank of cylinders the preset logic is followed by at least two lambda probes after cutting off the supply under pressure. The supply under pressure is not cut off if the temperature of the precatalyser or main catalyser is above a limit. The correlations are only determined if a signal from the probe, preferably the amplitude of the signal from the probe, is different from the signal before cutting off supply, and if the engine is operating in a homogenous manner before cut-off. While the supply under pressure is cut off from one bank of cylinders, the other bank(s) are operated with a poor mixture for longer than a preset time interval TM. An independent claim is also included for an internal combustion engine with direct injection and preferably fired by sparks, where the engine management system includes means of carrying out the monitoring process described above.