Enhanced Diagnosis for Small Engines

Small engines for non-automotive and two wheeler applications have a reduced number of sensors. For fulfilling emission regulations a cost effective way is an enhanced use of standard sensors in order to obtain more information from the existing sensors. The delivered information can then be used for an on-board diagnosis. Moreover, it is important to control the quality of the product during engine production; therefore an end-of-line cold engine test is often made. With this measure it is possible to detect faults, wrong tolerances or assembly in order not to deliver faulty engines to the customers.In this paper, an enhanced use of sensors for fault detection will be discussed. It is possible to obtain more information from the signal or to use the sensor for detecting other parameters. For extracting information signal analysis methods will be used with focus on the computational power need since the ECU performance is limited. The starter motor current is a useful indicator for detecting a lack of compression in an end-of-line check. Furthermore, it is possible to assign the fault to a specific cylinder by using one single sensor. It has to be considered that different faults have the same influence on the analyzed signals. Particular attention is put on the cylinder imbalance detection.