US Patent 10273906 Method and system for engine exhaust catalyst operations

Methods and systems are provided for controlling exhaust catalyst temperature during an engine cold-start by water injection. In one example, a method may include during the engine cold-start, injecting water into an intake of an engine based on the exhaust catalyst temperature and accumulating water molecules within an exhaust catalyst to generate heat within the exhaust catalyst. In this way, by generating and storing heat within the exhaust catalyst, the exhaust catalyst may be heated up rapidly, thus reducing catalyst light-off time.