Internal combustion engines having pre-ignition mitigation controls and methods for their operation

A method of operating an internal combustion engine comprising:

• determining whether an internal combustion engine is operating at conditions at which a super knock condition may occur, wherein the conditions at which the super knock condition may occur comprises an engine speed of less than 3000 rotations per minute and an indicated mean effective cylinder pressure of greater than 12 bar;
• in response to determining that the engine is operating at conditions at which the super knock condition may occur, injecting fuel with a fuel injector directly into a combustion chamber defined at least in part by an engine cylinder comprising a cylinder head and cylinder sidewalls and a piston that reciprocates within the engine cylinder, wherein injecting the fuel into the combustion chamber comprises injecting the fuel in a split injection mode in which fuel is injected into the combustion chamber in at least a primary injection pulse and a secondary injection pulse that occurs later than the primary injection pulse, wherein the secondary injection pulse injects 20% or less of a total amount fuel injected into the combustion chamber;
• and
• in response to determining that the internal combustion engine is operating at conditions at which the super knock condition is unlikely to occur, injecting the fuel into the combustion chamber in a single pulse injection.

An internal combustion engine comprising:

• an engine cylinder comprising a cylinder head and cylinder sidewalls;
• a piston that reciprocates within the engine cylinder, wherein the piston, the cylinder head, and the cylinder sidewalls at least partially define a combustion chamber;
• a fuel injector positioned to introduce fuel into the combustion chamber;
• and
• an engine control module in electronic communication with the fuel injector, the engine control module comprising a processor and a memory storing a computer readable instruction set that, when executed, causes the processor to:
• determine whether the internal combustion engine is operating at conditions at which a super knock condition may occur, wherein the conditions at which the super knock condition may occur comprises an engine speed of less than 3000 rotations per minute and an indicated mean effective cylinder pressure of greater than 12 bar;
• in response to determining that the engine is operating at conditions at which the super knock condition may occur, command the fuel injector to operate under a split injection mode in which the fuel injector:
• injects fuel is injected into the combustion chamber in a primary injection pulse;
• and
• injects fuel into the combustion chamber in a secondary injection pulse that occurs later than the primary injection pulse, maintaining an air-fuel ratio in the combustion chamber within 3% of a stoichiometric ratio;
• and
• in response to determining that the internal combustion engine is operating at conditions at which the super knock condition is unlikely to occur, command the one or more fuel injectors to inject the fuel into the combustion chamber in a single pulse injection.