A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.

Methods and systems are provided for using compression heating to heat a cylinder piston before cylinder combustion is resumed. Cylinder heating is achieved using combinations of slow unfueled engine rotation where the engine cylinders are heated via compression stroke heating, and slow compressor rotation where the cylinders are heated via compression heating. One or more intake or exhaust heaters may be concurrently operated to expedite cylinder heating.

Methods and systems are provided for using compression heating to heat a cylinder piston before cylinder combustion is resumed. Cylinder heating is achieved using combinations of slow unfueled engine rotation where the engine cylinders are heated via compression stroke heating, and slow compressor rotation where the cylinders are heated via compression heating. One or more intake or exhaust heaters may be concurrently operated to expedite cylinder heating.

A control device 100 for an internal combustion engine includes an in-cylinder oxygen concentration acquisition unit configured to acquire an in-cylinder oxygen concentration, an in-cylinder temperature acquisition unit configured to acquire an in-cylinder temperature, a target in-cylinder temperature acquisition unit configured to acquire a target in-cylinder temperature during main injection based on the in-cylinder oxygen concentration acquired by the in-cylinder oxygen concentration acquisition unit, and an in-cylinder oxygen concentration control unit configured to execute in-cylinder oxygen concentration control for controlling an in-cylinder oxygen concentration during pilot injection performed prior to the main injection based on the difference between the target in-cylinder temperature during the main injection acquired by the target in-cylinder temperature acquisition unit and the in-cylinder temperature acquired by the in-cylinder temperature acquisition unit.

A control device 100 for an internal combustion engine includes an in-cylinder oxygen concentration acquisition unit configured to acquire an in-cylinder oxygen concentration, an in-cylinder temperature acquisition unit configured to acquire an in-cylinder temperature, a target in-cylinder temperature acquisition unit configured to acquire a target in-cylinder temperature during main injection based on the in-cylinder oxygen concentration acquired by the in-cylinder oxygen concentration acquisition unit, and an in-cylinder oxygen concentration control unit configured to execute in-cylinder oxygen concentration control for controlling an in-cylinder oxygen concentration during pilot injection performed prior to the main injection based on the difference between the target in-cylinder temperature during the main injection acquired by the target in-cylinder temperature acquisition unit and the in-cylinder temperature acquired by the in-cylinder temperature acquisition unit.

A torque requesting module generates a first torque request for a spark ignition engine based on driver input. A torque conversion module converts the first torque request into a second torque request. A model predictive control (MPC) module determines a set of target values based on the second torque request, a model of the engine, and a matrix having dimensions of (m+n) by (m+n). n is an integer greater than zero that is equal to a number of lower boundary constraints used in the determination of the set of target values. m is an integer greater than zero that is equal to a number of constraints used in the determination of the set of target values other than the lower boundary constraints. An actuator module controls opening of an engine actuator based on a first one of the target values.