Exhaust Manifold Pressue Estimation on a Turbocharged SI-Engine with Wastegate

Abstract

In turbocharged engines with wastegate the exhaust pressure can change rapidly. Amethod to estimate the exhaust manifold pressure is presented for diagnosis of wastegate and turbocharger on spark-ignited engines. It does not require any extra sensors in the exhaust system after the calibration. A non-linear model is developed of the exhaust pressure. Estimates of the exhaust manifold pressure relies on infonnation from an air-to-cylinder observer and a static map of stationary exhaust pressure. The exhaust manifold pressureestimator is validated using a series of wastegate steps on a turbocharged SAAB 2.3 dm3 SI-engine. The exhaust pressure estimation is designed for steady-state conditions and the validation shows that it works well and converges within 1 to 4 seconds.