Model-based engine fault detection using cylinder pressure estimates from nonlinear observers

There are two indicated torque input observers presented in paper. The input estimation problem is transformed into the control tracking problem. The sliding mode control with integrator and PI with feedforward control are used for tracking control blocks. The indicated torque estimations are applied to detect engine firing faults. Cylinder pressure centroid and cylinder pressure difference approaches for engine diagnostics are also discussed in this paper. Simulation results for a six-cylinder engine with abnormal combustion are plotted to show engine combustion problems