An adsorption-precipitation model for the formation of injector external deposits in internal combustion engines

•Kinetic model for gasoline injector deposit formation in engines is developed.•Injector leakage causes accumulation of fuel near the nozzle post-injection.•The leaked fuel degrades under the action of NOx and O2 in the quench layer.•Radical chain oxidation takes place involving a branching reaction with NO.•The pressure drop during the power stroke causes the leaked droplet to boil.