Detection of Exhaust Manifold Leaks on a Turbocharged SI-Engine with Wastegate

Abstract

Emissions from modern SI-engines are reduced by a three way catalyst. However if there are leaks in the exhaust system before the catalyst emissions increase for two reasons. First the untreated emissions leak out. Second which is worse, due to waves in the exhaust system, oxygen leaks into the manifold and causes an oxygen sensor offset. The result is increased emissions as the air/fuel controller makes the engine run rich. Here a method to detect leakages in the exhaust manifold is presented. The sensors used are binary oxygen sensor(s), intake manifold pressure and temperature, and the air mass flow sensor. Injection time is also used to estimate air/fuel ratio. Experimental results are shown with measurements from a turbo charged SAAB SI production engine with wastegate.

MVEM-Based Fault Diagnosis of Automotive Engines Using Dempster–Shafer Theory and Multiple Hypotheses Testing

“…Leak detection rates obtained in this paper are low and comparable to those obtained in [24] that indicate that leaks are not easily detectable as an 85% missed detection rate was reported. Some detections were obtained at low loads.…”

“…Work on exhaust manifold leaks is sparse. Leak models based on pressure difference and oxygen content models for exhaust leak detection is described in [24] where some initial results with high missed detection rates (85%) were reported. In this paper, leak detection using a new leak model is attempted.…”

“…The DST framework also provides ways of dealing with conflict of evidence. Apart from the above innovations, the models used in [1], [2], [24], and [25] are simple MVEM structures that pertain to a few engine subsystems. In this paper, the MVEM encompasses a complete engine system.…”

Real-time estimation of the volumetric efficiency in spark ignition engines using an adaptive sliding-mode observer

“…As shown, the test is repeated at three engine speeds (2500 r/min, 3000 r/min and 3500 r/min), at each of which the engine torque has three levels. The engine mass flow is detected on the basis of equation (4) and the volumetric efficiency from equation (5). The results of the cylinder flow estimated by using the proposed observer with a sign function (equation (9)) are plotted in Figure 5.…”

“…There are some common solutions used to reduce the fuel consumption and the tailpipe emissions of a vehicle such as optimizing the vehicle's engine performance, 1 utilizing fault diagnosis, 2 managing the flow of fresh air 3 and adding new components, e.g. three-way catalyst converters 4,5 and exhaust gas recirculation systems. 6 Optimization of the engine performance is realized by controlling the important parameters of the engine including the air-to-fuel ratio of the engine.…”