A control apparatus for an internal combustion engine comprises a throttle upstream pressure estimation unit which calculates, based on an AFS intake air amount from an AFS and an intake manifold pressure, an average density ave(n) in a region combining a supercharged portion from a downstream of a compressor to an upstream of a throttle valve and an intake manifold, and estimates a throttle upstream pressure based on the intake manifold pressure and the average density ave(n). Further, the throttle upstream pressure estimation unit learns a relationship between a throttle opening degree and an effective opening area to correct a throttle upstream pressure estimated value (estimated P2) based on a range of a throttle opening degree learning value, the throttle opening degree learning value, and a dispersion of the actual throttle opening degree error.

A method for determining the atmospheric pressure for a combustion engine having a cylinder, a throttle valve and an air intake valve admitting air into the cylinder, as well as a pressure sensor between the throttle valve and the intake valve. The method including the following steps: measuring a first pressure at a given angular position of the engine; measuring a second pressure at a predetermined time interval after the measuring of the first pressure; from other parameters, determining an estimated value for the atmospheric pressure. The time interval corresponding to a half-period of a pressure pulsation experienced as air is admitted into the engine, and an average pressure corresponding to the mean of the first pressure and of the second pressure being used, with the other possible parameters, to determine the atmospheric pressure.

A compression ignition engine, commercial vehicle comprising such an engine, and a method for improving starting behaviour of such an engine. The engine is operable in a normal mode or a cold start mode. In the normal mode, a fuel injection system is controlled to inject a main fuel injection in a single pulse. In the cold start mode, the main fuel injection is split into a first split main and a second split main. The fuel injection system is controlled to inject the first and second split main in two distinct pulses, wherein the first split main is injected at a delayed timing for initiating a diffusion combustion phase in the pressurized combustion chamber, and wherein the second split main is injected during the diffusion combustion phase into the already combusting air-fuel mix.