Approach for reducing injector fouling and thermal degradation for a multi-injector engine system

A method of operating an engine of a vehicle, the engine having a variable engine output, the method comprising:

• during a first engine output, delivering gasoline to at least a cylinder of the engine via a first injector and directly injecting ethanol directly into said cylinder via a second injector;
• and
• during a second engine output lower than said first engine output, delivering gasoline to said at least a cylinder of the engine and intermittently injecting at least a purging substance directly into said cylinder via said second injector;
• wherein a frequency of said intermittent injection of said purging substance is varied responsive to an operating condition, and where said purging substance includes at least one of gasoline, ethanol, and water.

A method of operating an internal combustion engine for a road vehicle, the method comprising:

• delivering a first fuel to at least a cylinder of the engine via a first injector and combusting at least said first fuel to produce a first level of torque;
• injecting a purging substance directly into said cylinder via a second injector to purge said second injector during at least one engine cycle prior to an increase in torque produced by the engine from said first level of torque to a second level of torque;
• delivering said first fuel to said cylinder via said first injector, injecting a second fuel directly into said cylinder via the second injector, increasing a level of boost provided to the engine, and combusting at least said first fuel and said second fuel to produce said second level of torque greater than said first level of torque;
• wherein said first fuel includes gasoline, said second fuel includes an alcohol, and said purging substance includes at least one of gasoline and said alcohol.