Models that employ both measurable engine parameters as well as predictable engine parameters may be used to determine when a thermostat is malfunctioning before the thermostat malfunction results in an engine breakdown. Particular models may be used to provide an estimated coolant temperature and an estimated thermostat position. The estimated coolant temperature can be compared to an actual measured engine coolant temperature. The estimated thermostat position can be evaluated with respect to what the thermostat position should be given a particular engine coolant temperature. In some cases, comparison between a healthy model and a faulty model may be used to ascertain thermostat health.

Models that employ both measurable engine parameters as well as predictable engine parameters may be used to determine when a thermostat is malfunctioning before the thermostat malfunction results in an engine breakdown. Particular models may be used to provide an estimated coolant temperature and an estimated thermostat position. The estimated coolant temperature can be compared to an actual measured engine coolant temperature. The estimated thermostat position can be evaluated with respect to what the thermostat position should be given a particular engine coolant temperature. In some cases, comparison between a healthy model and a faulty model may be used to ascertain thermostat health.

Models that employ both measurable engine parameters as well as predictable engine parameters may be used to determine when a thermostat is malfunctioning before the thermostat malfunction results in an engine breakdown. Particular models may be used to provide an estimated coolant temperature and an estimated thermostat position. The estimated coolant temperature can be compared to an actual measured engine coolant temperature. The estimated thermostat position can be evaluated with respect to what the thermostat position should be given a particular engine coolant temperature. In some cases, comparison between a healthy model and a faulty model may be used to ascertain thermostat health.

Methods are provided for engine coolant system diagnostics. In one example, engine coolant system malfunction is indicated based on an engine coolant temperature inference model, whereas in another example engine coolant system malfunction is indicated based on a time-based monitor, where the inference model is enabled at ambient temperatures above a predetermined threshold, and where the time-based monitor is enabled at ambient temperatures below the predetermined threshold. In this way, accurate engine coolant system diagnosis may be accomplished under ambient temperature conditions wherein the engine coolant temperature inference model may be compromised.

An exhaust purification system of an internal combustion engine comprises a filter 23 arranged in an exhaust passage 23 of an internal combustion engine in which a plurality of cylinders 61, 62, 63, 64 cooled by cooling water are provided and trapping particulate matter in exhaust gas, a wall temperature calculation part 51 configured to calculate or detect wall temperatures of a predetermined number of equal to or more than two cylinders among the plurality of cylinders, and a PM amount calculation part 52 configured to calculate an amount of particulate matter discharged from the plurality of cylinders to the exhaust passage based on the wall temperatures calculated or detected by the wall temperature calculation part.

A controller for a vehicle executes a base temperature calculation process that calculates a base temperature of a component of the internal combustion engine, a correction value calculation process that calculates a correction value, a vehicle line reflection process when the vehicle including the component of which temperature is estimated is a temperature-estimated vehicle that is in a line of vehicles in order to reflect, on the correction value, a tendency of the component to be less cooled when the temperature-estimated vehicle is a trailing vehicle than when the temperature-estimated vehicle is a leading vehicle, a rearmost reflection process when the temperature-estimated vehicle is in the line of vehicles in order to reflect, on the correction value, a tendency of the component to be more cooled when the temperature-estimated vehicle is a rearmost vehicle, and a component temperature estimation process that corrects the base temperature with the correction value.

A controller for a vehicle executes a base temperature calculation process that calculates a base temperature of a component of the internal combustion engine, a correction value calculation process that calculates a correction value, a vehicle line reflection process when the vehicle including the component of which temperature is estimated is a temperature-estimated vehicle that is in a line of vehicles in order to reflect, on the correction value, a tendency of the component to be less cooled when the temperature-estimated vehicle is a trailing vehicle than when the temperature-estimated vehicle is a leading vehicle, a rearmost reflection process when the temperature-estimated vehicle is in the line of vehicles in order to reflect, on the correction value, a tendency of the component to be more cooled when the temperature-estimated vehicle is a rearmost vehicle, and a component temperature estimation process that corrects the base temperature with the correction value.

Methods and systems are provided for monitoring a status of a heater core isolation valve (HCIV) housing in an engine coolant circuit including a first coolant loop and a second coolant loop. In one example, a method may include indicating degradation of the HCIV based on a difference between a first coolant loop temperature and a second coolant loop temperature upon activation of coolant system pumps and deactivation of a positive temperature coefficient (PTC) heater housed in the cabin heating loop.

A cooling system for a marine inboard internal combustion engine includes at least one engine cooling passage disposed in thermal communication with heat emitting portions of the engine. A pump is in fluid communication with the at least one engine cooling passage. The pump draws cooling water out of the at least one engine cooling passage. At least one outlet drain is downstream of the pump for discharging the cooling water that was pumped out of the at least one cooling passage. A switch activates the pump in response to the following: an operator command to stop the engine and/or a speed of the engine being below a threshold speed.

A cooling system includes an electric pump, a cooling target temperature sensor, a coolant temperature sensor, and an electronic control unit. The electric pump pumps a coolant to a circulation channel connected to an inlet and an outlet of a cooling channel in which heat is exchanged with a cooling target. The cooling target temperature sensor detects a cooling target temperature. The coolant temperature sensor is arranged upstream of the inlet in the circulation channel, and detects a coolant temperature. The electronic control unit controls driving of the electric pump so that a discharge flow rate of the electric pump matches a target flow rate, and sets the target flow rate using an equation based on a reference value obtained by dividing a difference between the cooling target temperature and a target cooling temperature of the cooling target by a difference between the cooling target temperature and the coolant temperature.