Influences of engine faults on pollutant emission

The technical state of the internal combustion engine systems influences the level of pollutant emissions. Depending on the fault, these are recognized by the OBD system. Often, the car is functional and in good conditions to drive even when some defects are diagnosed. The study refers to the test on the dynamometer stand of four cars equipped with the same type of engine, Renault K7M. Controlled engine defects were induced. The intended devices are decommissioned by disconnecting the electrical connection. That is considered a defective. The concentrations of pollutant emissions were measured in several test regimes both in good operating condition and in defective conditions. The defects were related to the air pressure transducer in the intake manifold, the oxygen sensor in the exhaust manifold, and to one of the four injectors. Results shown how the induced engine defects influence the concentrations of pollutant emissions. It is found that, if an injector does not work, the emission level increases significantly, more than if the oxygen sensor does not work. The air pressure sensor failure in the intake manifold had a lesser influence on pollutant emissions. Intake manifold air pressure sensor malfunction had a lesser influence on pollutant emissions.