Abstract: An ignition system for a vehicle internal combustion engine (12) has a capsule defining a pre-chamber (136), an ignition fuel supply system (500) configured to inject an ignition fuel to the pre-chamber to create an ignition fuel-air mix in the pre-chamber, an ignition surface (137) within the pre-chamber, the ignition surface being defined by an interior surface of the capsule and configured to be contacted by the ignition fuel in the pre-chamber to thereby ignite the ignition fuel by hot surface ignition, and at least one jet nozzle (152). The ignition fuel is characterised by having a carbon content by mass less than 65%, a hot surface ignition temperature less than 500 deg C., and a volumetric energy density (LHV) greater than 18 MJ/L. The at least one jet nozzle is configured such that ignition of the ignition fuel by contact with the ignition surface causes at least one of hot gases, partially combusted fuel and flames to leave the pre-chamber through the at least one jet nozzle.

Abstract: A method of lubricating and cleaning a fuel injector of a fuel injection system of an internal combustion engine during running of the engine including delivering both a lubricant and a cleaning additive to the injector. The injector injects directly into the combustion chamber of the engine. The lubricant and cleaning additive are delivered to the fuel exit area of the injector.