On-line cylinder fault diagnostics for internal combustion engines

The ability to continuously monitor internal combustion engines for the existence and location of faults can improve engine reliability and reduce operating costs. The diagnostics method is based on recording the engine speed fluctuations at the flywheel and at the front end of the engine over one combustion cycle. From the speed fluctuations, the cylinder-to-cylinder variations of the net engine torque are computed. The performance deterioration of an individual cylinder is detected as a drop of computed torque. The diagnostic hardware consists of a digital engine speed data acquisition system and an embedded controller and is suited for in-vehicle installation. The method, suited for any multicylinder engine, detects the location and severity of faults during normal engine operation. Adjustments for individual engines of the same class are not required