This paper presents the vibration analysis of an internal combustion engine, using different fuel blends, to identify fault operating conditions. A purpose built engine test bench was used and the fault studied was misfire. Three fuel blends were used: E8, E20 and E30. Fast Fourier transform was applied to the signals. A comparison between normal and faulty operating conditions was carried with every fuel used, looking for characteristic frequency components, to assess the validity of past studies on misfire performed on pure gasoline. The results show that the behavior using the different fuel blends is similar to the one reported on pure gasoline, and that the frequency components that differentiate normal and faulty conditions are also present on the fuel blends. Statistical characteristics were extracted from the signals in the frequency domain to simplify the identification process.