Abstract: A urea water agitation control device has an agitation control portion and a temperature sensor which detects a temperature of a urea water. The agitation control portion operates an agitation portion in a specified period which includes a part of a period in which the urea water temperature detected by the temperature sensor is kept at a eutectic point and the urea water radiates a latent heat of solidification.

Abstract: A rotation acquisition unit acquires a rotation signal correlated with a rotational state of an internal combustion engine. An analysis unit performs frequency analysis of the rotation signal acquired with the rotation acquisition unit. An inter-cylinder determination unit determines whether an inter-cylinder component is smaller than an inter-cylinder threshold representing occurrence of misfire. The inter-cylinder component is a frequency component of an inter-cylinder cycle. The inter-cylinder cycle is computed by dividing an ignition cycle, which is one burning cycle of the internal combustion engine, by a number of cylinders of the internal combustion engine.

Abstract: A urea water agitation control device has an agitation control portion and a temperature sensor which detects a temperature of a urea water. The agitation control portion operates an agitation portion in a specified period which includes a part of a period in which the urea water temperature detected by the temperature sensor is kept at a eutectic point and the urea water radiates a latent heat of solidification.

Abstract: A rotation acquisition unit acquires a rotation signal correlated with a rotational state of an internal combustion engine. An analysis unit performs frequency analysis of the rotation signal acquired with the rotation acquisition unit. An inter-cylinder determination unit determines whether an inter-cylinder component is smaller than an inter-cylinder threshold representing occurrence of misfire. The inter-cylinder component is a frequency component of an inter-cylinder cycle. The inter-cylinder cycle is computed by dividing an ignition cycle, which is one burning cycle of the internal combustion engine, by a number of cylinders of the internal combustion engine.

Abstract: A fuel injection is carried out as n split injections. Each of injection quantities is defined by dividing an injection quantity into n fuel injections. A FCCB correction and an ISC correction are carried out while n split injection cycles are performed. A value obtained by adding up an FCCB correction for each injection cycle and an ISC correction for each injection cycle is updated and stored as a learned injection quantity. The learned injection quantity is calculated as an injection quantity correction for each cylinder to be added to a command injection quantity for each injection cycle.

Abstract: A fuel injection is carried out as n split injections. Each of injection quantities is defined by dividing an injection quantity into n fuel injections. A FCCB correction and an ISC correction are carried out while n split injection cycles are performed. A value obtained by adding up an FCCB correction for each injection cycle and an ISC correction for each injection cycle is updated and stored as a learned injection quantity. The learned injection quantity is calculated as an injection quantity correction for each cylinder to be added to a command injection quantity for each injection cycle.