This study will focus on the detection of misfire using Acoustic emission sensor in a multi-cylinder diesel engine. Detection of misfire is important since this malfunction can cause the engine to stall in a short time. In order to investigate the misfire, an experimental engine was run with and without injection of the fuel in the first cylinder. The acoustic emission signal was acquired synchronously with the crank angle signal, in order to have a reference for the transformation from time to angular domain. The AE signal was then processed using the squared envelope spectrum to highlight angle-periodic modulations in the signal’s power (cyclic bursts). This study will present the effectiveness of this combination of sensor technology and signal processing to detect misfire in a six-cylinder diesel engine connected to a hydraulic dynamometer.