Fault isolation and analysis for IC engine onboard diagnostics

The development of diagnostic algorithms for the detection of misfiring cylinders in an internal combustion engine is described. The algorithms are applied to a measurement of engine angular velocity obtained by means of an inexpensive noncontacting sensor, and they are applicable to many classes of internal combustion engines, including spark and compression ignition engines. The computational efficiency of the algorithms is such that the onboard implementation of these diagnostic procedures is feasible with currently used microprocessors. Experimental work conducted on production vehicles has confirmed that it is possible to apply very robust algorithms with minimal hardware and computational overhead