Patent ID: 7669584

Claim:
Method for controlling operation of an internal combustion engine, the engine ongoingly operative in repetitive cycles each cycle comprising intake, compression, expansion, and exhaust strokes, the method comprising: monitoring in-cylinder pressure and a corresponding engine crank position; operating the engine in a motoring mode and determining a plurality of instantaneous in-cylinder pressure states and corresponding engine crank positions; operating the engine in a cylinder firing mode and determining a plurality of instantaneous in-cylinder pressure states at the corresponding engine crank positions; determining a plurality of pressure ratios during ongoing engine operation at the corresponding engine crank positions based upon the instantaneous in-cylinder pressure states, each pressure ratio comprising a ratio between the instantaneous in-cylinder pressure state at the engine crank position determined when operating the engine in the motoring mode and the corresponding instantaneous in-cylinder pressure state at the engine crank position determined when operating the engine in the firing mode; and, determining an instantaneous crank angle error associated with the pressure ratios determined during the ongoing engine operation.