Torque Estimation and Misfire Detection using Block Angular Acceleration

This work examines the possibility of detecting misfires via measurements of the angular acceleration of the engine block. Measurements were taken on a production 4-cylinder engine which was modeled as a single degree of freedom torsional oscillator. The torque waveform was estimated and compared to the torque calculated via cylinder pressure measurements. Further analysis was conducted in the frequency domain. Results indicate that metrics based on low frequency information were most reliable, but this is impractical for vehicular applications. The accuracy of high frequency metrics was degraded due to the limitations of the model and the non-rigid behavior of the block at high engine speeds.