A Numerical Study of a Simple Stochastic/Deterministic Model of   Cycle-to-Cycle Combustion Fluctuations in Spark Ignition Engines
  We examine a simple, fuel-air, model of combustion in a 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-fuel mixture. The largest influence was found in the limit of a lean combustion. The possible effect of nonlinearities in the combustion process has been also discussed. 
G. Litak, M. Wendeker, M. Krupa and J. Czarnigowski