Ignition system utilizing igniter and gas injector

A method of initiating combustion within an engine, comprising:

• locally heating a fuel mixture within the engine to initiate combustion during a first mode of engine operation;
• ceasing the local heating during a second mode of engine operation;
• and
• injecting a non-combustible gas directly into a combustion chamber of the engine during the second mode of engine operation to initiate auto-ignition of the fuel mixture.

An engine, comprising:

• an engine block at least partially defining a cylinder;
• a piston recipratingly disposed within the cylinder to form a combustion chamber;
• a first injector configured to inject fuel into the combustion chamber;
• a supply of air in selective communication with the combustion chamber;
• an igniter located to locally heat a mixture of the fuel and air;
• and
• a second injector configured to inject a non-combustible gas directly into the combustion chamber.