Abstract: For gaseous fuels that are injected directly into a combustion chamber the mass flow rate through an injection valve can be influenced by changes in the in-cylinder pressure. A method and apparatus are provided for accurately metering a gaseous into a combustion chamber of an internal combustion engine. The method comprises inputting a fueling command; determining from said fueling command a baseline pulse width of an injection event, based upon a baseline pressure differential across a fuel injection valve; estimating the difference between said baseline pressure differential and an actual pressure differential; calculating a corrected pulse width by applying at least one correction factor to said baseline pulse width, wherein said correction factor is a function of the estimated difference between said baseline pressure differential and said actual pressure differential.