2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80640We examine a simple, fuel-air, model of combustion in spark ignition (si) engine with indirect injection. In our two fluid model, variations of fuel mass burned in cycle sequences appear due to stochastic fluctuations of a fuel feed amount. We have shown that a small amplitude of these fluctuations affects considerably the stability of a combustion process strongly depending on the quality of air-fulel mixture. The largest influence was found in the limit of a lean combustion. The possible effect of nonlinearities in the combustion process were also discussed.9 pages, 3 figures, submitted to Journal of Vibration and ControlChaotic Dynamicstext