A system and method for improving engine starting and stopping is described. In one example, turbine vanes are adjusted to increase engine exhaust backpressure to reduce engine stopping time and to limit engine speed overshoot during engine starting. The system and method may reduce engine emissions and improve a vehicle driving experience.

Methods and systems are provided for inferring spark plug fouling due to accumulation of fuel additives thereon. In one example, an engine controller may infer spark plug fouling due to accumulation of fuel additive based on a combination of engine operating parameters correlated with spark plug health. For example, the engine operating parameters may include a change in an adaptive knock term, an engine pre-ignition rate, and engine exhaust oxygen sensor switching frequency over a vehicle drive cycle, and an engine misfire rate.

A method of controlling temperature of an engine aftertreatment system includes directing an exhaust heating device in an engine aftertreatment system to apply heat to the engine aftertreatment system; opening at least one of one or more intake valves and one or more exhaust valves of an engine coupled to the engine aftertreatment system; and pulsing, by an engine starter of the engine, the engine to generate airflow from the engine that moves the applied heat from the exhaust heating device downstream the engine aftertreatment system.