Engine and coolant system control systems and methods

A coolant control system of a vehicle comprising:

• a coolant pump that pumps coolant to a heat exchanger that is different than a radiator of the vehicle;
• the heat exchanger;
• a diesel exhaust fluid (DEF) injector that injects a DEF into an exhaust system of the vehicle and that receives coolant output from the heat exchanger;
• a fuel heat exchanger that receives fuel flowing from a fuel rail to a fuel tank of the vehicle, that receives coolant output from the DEF injector, and that transfers heat between coolant flowing through the fuel heat exchanger and fuel flowing through the fuel heat exchanger,
• wherein the coolant pump receives coolant output from the fuel heat exchanger;
• and
• an engine control module (ECM) configured to:
• determine a first requested speed of the coolant pump for DEF injector cooling;
• determine a second requested speed of the coolant pump for fuel cooling using the fuel heat exchanger;
• determine a target speed of the coolant pump based on the first and second requested speeds;
• control a speed of the coolant pump based on the target speed;
• and
• based on at least one of the first requested speed and the second requested speed, selectively increase at least one of:
• opening of a valve that controls a flow rate of fuel flowing from the fuel rail to the fuel tank;
• a flow rate of fuel from fuel injectors of an engine to the fuel tank;
• and
• the target speed of the coolant pump,
• wherein the ECM is configured to, when the first requested speed is greater than or equal to a predetermined speed, both:
• selectively increase the opening of the valve that controls the flow rate of fuel flowing from the fuel rail to the fuel tank;
• and
• increase the flow rate of fuel from fuel injectors of the engine to the fuel tank.

A coolant control system of a vehicle comprising:

• a coolant pump that pumps coolant to a heat exchanger that is different than a radiator of the vehicle;
• the heat exchanger;
• a diesel exhaust fluid (DEF) injector that injects a DEF into an exhaust system of the vehicle and that receives coolant output from the heat exchanger;
• a fuel heat exchanger that receives fuel flowing from a fuel rail to a fuel tank of the vehicle, that receives coolant output from the DEF injector, and that transfers heat between coolant flowing through the fuel heat exchanger and fuel flowing through the fuel heat exchanger,
• wherein the coolant pump receives coolant output from the fuel heat exchanger;
• and
• an engine control module (ECM) configured to:
• determine a first requested speed of the coolant pump for DEF injector cooling;
• determine a second requested speed of the coolant pump for fuel cooling using the fuel heat exchanger;
• determine a target speed of the coolant pump based on the first and second requested speeds;
• control a speed of the coolant pump based on the target speed;
• and
• based on at least one of the first requested speed and the second requested speed, selectively increase at least one of:
• opening of a valve that controls a flow rate of fuel flowing from the fuel rail to the fuel tank;
• a flow rate of fuel from fuel injectors of an engine to the fuel tank;
• and
• the target speed of the coolant pump,
• wherein the ECM is further configured to actuate an aerodynamic shutter to an open position when all of:
• a speed of a fan that pushes air to the heat exchanger and the radiator is less than a predetermined value;
• a speed of the vehicle is greater than a predetermined value;
• and
• the target speed of the coolant pump is equal to a predetermined maximum speed of the coolant pump.