Method for a
machine, comprising: Indicating cylinder-to-cylinder imbalance based on each of the exhaust air-fuel ratio (LAMavg) estimated by an
exhaust gas sensor (126), the
exhaust manifold pressure (Pavg) estimated by a
pressure sensor (124), and the individual cylinder torque (TQavg) estimated by a
crankshaft torque sensor (200, 210); wherein the indicating based on the exhaust air-fuel ratio (LAMavg) is based on the exhaust air-fuel ratio (LAMavg) weighted with a first
confidence factor (c1), the indicating based on the
exhaust manifold pressure (Pavg), based on exhaust pressure weighted by a second
confidence factor (c2), and specifying based on individual cylinder torque (TQavg) based on the individual cylinder torque (TQavg) weighted by a third
confidence factor (c3); further comprising calculating a combined imbalance parameter based on the weighted exhaust air-fuel ratio (LAMavg), the weighted
exhaust manifold pressure (Pavg), and the weighted individual cylinder torque (TQavg) for each engine cylinder; and by means of a control device (12) provided with computer-readable instructions stored in a non-
volatile memory, Determining a first confidence factor (c1) of the estimated
exhaust gas air-fuel ratio (LAMavg) based on
fuel type, Determining a second confidence factor (c2) of the estimated exhaust pressure based on
valve timing, Determining a third confidence factor (c3) of the estimated individual Cylinder torque (TQavg) based on exhaust temperature, indicating cylinder-to-cylinder imbalance based on two or more of the estimated exhaust air-fuel ratio (LAMavg) weighted by the first confidence factor (c1), the estimated exhaust manifold pressure (Pavg) weighted by the second confidence factor (c2) and the estimated individual cylinder torque (TQavg) weighted by the third confidence factor (c3), and applying an air-fuel ratio correction to one or more cylinders (30) based on the indication.