Self-cleaning for torch ignitors

A method of operating and cleaning a torch ignitor for continuous ignition comprising:

• issuing a fuel-lean flow through a combustion chamber of the torch ignitor, wherein the fuel-lean flow has a first fuel-air ratio;
• heating interior surfaces of the torch ignitor, wherein the fuel-lean flow reacts with carbon deposits on the interior surfaces to remove the carbon deposits, wherein the interior surfaces include at least one of:
• a surface of a dome of the combustion chamber, a combustor liner surface of the combustion chamber, and interior surface of an exhaust tube of the combustion chamber, and/or glow plug surfaces in the combustion chamber, wherein the torch ignitor is aboard an aircraft and wherein issuing the fuel-lean flow and heating the interior surfaces are performed as a self-cleaning cycle intermittently during flight of the aircraft, wherein the self-cleaning cycle is repeated as a series;
• and
• issuing an air-fuel mixture into the combustion chamber which has a second fuel-air ratio that is higher than the first fuel-air ratio of the fuel-lean flow, is performed as a series and intermittently between the series of the self-cleaning cycles, so issuing the fuel-lean flow, which has the first fuel-air ratio, of each of the series of self-cleaning cycles alternates with each of the series of issuing the air-fuel mixture, which has the second fuel air ratio.