AIR/FUEL RATIO IMBALANCE DETECTION DEVICE FOR INTERNAL COMBUSTION ENGINE

A plurality of cylinders are provided. An in-cylinder pressure sensor is mounted on each of the plurality of cylinders. A combustion parameter (e.g., the amount of generated heat) is calculated from the output of the in-cylinder pressure sensor. The air-fuel ratio for a cylinder is enleaned by reducing a fuel injection amount until the combustion parameter coincides with a predetermined value. Each cylinder is subjected to fuel injection amount reduction control so that the combustion parameter coincides with the predetermined value. The air-fuel ratio for each cylinder is then calculated in accordance with the reduction amount of fuel injection amount. The calculated air-fuel ratios are compared to detect an air-fuel ratio imbalance between the cylinders.