Systems and methods for conducting onboard engine cleaning routines in a vehicle
Methods and systems are provided for mitigating issues related to sluggish engine performance. In one example, a method comprises, responsive to an indication of degradation of one or more cylinders in the engine, reducing carbon buildup associated with the one or more cylinders via injecting a diesel exhaust fluid into an intake manifold of the engine while the engine is combusting air and fuel. In this way, a water content of the diesel exhaust fluid may be vaporized in the one or more engine cylinders, which may effectively reduce the carbon buildup.
1. A method comprising:
in a first operating condition of a vehicle, including an indication of degradation of one or more cylinders of an engine and a lack of degradation indicated in an exhaust gas recirculation system, injecting a diesel exhaust fluid into an intake manifold of the engine with an exhaust gas recirculation valve closed to mitigate the degradation of the one or more cylinders; and
in a second operating condition of the vehicle, including an indication of degradation in the exhaust gas recirculation system, and either a lack of degradation in the one or more cylinders and/or the indication of degradation in the one or more cylinders of the engine, injecting the diesel exhaust fluid into the intake manifold of the engine with the exhaust gas recirculation valve open to mitigate the degradation of the exhaust gas recirculation system.
2. The method of claim 1 , wherein the indication of degradation of one or more cylinders includes an indication of a torque measured in the one or more cylinders of the engine being below an expected or desired torque, and/or an indication of a pressure in the one or more cylinders of the engine being below an expected or desired pressure.
3. The method of claim 1 , further comprising injecting the diesel exhaust fluid into the intake manifold while the engine is combusting air and fuel during the first operating condition; and
stopping the injecting of the diesel exhaust fluid into the intake manifold in response to an indication that the degradation of the one or more engine cylinders has been mitigated, where mitigating the degradation of the one or more engine cylinders includes reducing or removing carbon buildup associated with the one or more engine cylinders.
4. The method of claim 1 , further comprising injecting the diesel exhaust fluid into the intake manifold while the engine is rotated unfueled in a forward direction in the second condition, where injecting the diesel exhaust fluid and rotating the engine unfueled is conducted for a first predetermined duration; and
in response to the first predetermined duration elapsing, activating the engine to combust air and fuel with one engine cylinder not receiving fuel;
maintaining the injecting the diesel exhaust fluid into the intake manifold, and maintaining the exhaust gas recirculation valve open while the engine is combusting air and fuel, and stopping injecting the diesel exhaust fluid and closing the exhaust gas recirculation valve in response to an indication that the degradation in the exhaust gas recirculation system has been mitigated, where mitigating the degradation in the exhaust gas recirculation system includes reducing or removing carbon buildup in an exhaust gas recirculation passage of the exhaust gas recirculation system and/or reducing or removing carbon buildup associated with the exhaust gas recirculation valve.
5. The method of claim 4 , wherein the one engine cylinder not receiving fuel does not comprise the one or more cylinders of the engine with the indicated degradation in the second condition.
6. The method of claim 1 , wherein the indication of degradation in the exhaust gas recirculation system is in response to a flow in the exhaust gas recirculation system being below a desired flow under predetermined vehicle operating conditions when the exhaust gas recirculation valve is open, and/or in response to the flow in the exhaust gas recirculation system being above the desired flow under conditions when the exhaust gas recirculation valve is closed.