Methods and systems for a multi-fuel engine

A system for an engine, comprising:

• a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the engine cause the controller to:
• operate the engine with a first amount of gaseous fuel and a second amount of liquid fuel determined according to engine speed, a gaseous torque estimation, a liquid torque estimation, and a first substitution ratio;
• determine a relative error between the gaseous torque estimation and the liquid torque estimation;
• correct the gaseous torque estimation based at least in part on the relative error;
• and
• operate the engine with a third amount of gaseous fuel and a fourth amount of liquid fuel determined based at least in part on the corrected gaseous torque estimation and the liquid torque estimation.

A system for an engine, comprising:

• a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the engine cause the controller to:
• operate the engine at a variable substitution ratio of gaseous fuel and liquid fuel while adjusting amounts of gaseous fuel and liquid fuel to maintain torque;
• maintain engine speed at a target speed by feedback adjusting the amounts of gaseous fuel and liquid fuel while varying the substitution ratio;
• correlate the feedback adjustments in the amounts of gaseous fuel and liquid fuel to error in gas admission valve gaseous fuel delivery;
• and
• adjust control of gas admission valve operation based on the error.