Fault effect analysis of the exhaust manifold leakage for a turbocharged spark ignition engine

Abstract

Fault monitoring in internal-combustion engines is crucial for keeping the vehicle performance within the acceptable standards of emission levels and drivers’ demands. This paper analyses how a vehicle’s performance and engine variables are affected by a leakage fault in the exhaust manifold. The threshold leakage that causes the vehicle to exceed the emission standards is determined for a class M1 vehicle tested on a chassis dynamometer over the New European Driving Cycle. It is shown that, when a leakage of 6 mm diameter on the exhaust manifold is introduced, the vehicle emissions exceed those specified in the European 2013 on-board diagnostics standard. In addition, the effects of the said leakage fault on the performance of a 1.7 l turbocharged gasoline engine are analysed at different speed–torque operating points by running the engine in a test cell. The results show that, for this 6 mm leakage, at most operating points the driver cannot notice any reduction in the engine torque. Using the engine performance analysis, a fault effect map for the turbocharged gasoline engine is obtained. This helps to design monitoring algorithms for detection of the exhaust manifold leakage fault. As an application of the map, a strategy is presented on the basis of a comparison between the measured and the estimated pressures downstream of the turbine for the purpose of detecting the exhaust manifold leakage.