Smoke Limitation This requires high injection pressure to improve the atomisation of the fuel injected into the cylinders. By maintaining high fuel pressures at low engine speeds, the ECM maximises the atomisation of the fuel for conditions where turbulence in the combustion chamber is reduced. The strategy contained in the ECM does not allow more fuel to be injected than there is oxygen in the cylinders. Active Surge Damping Active surge damping is implemented to prevent the engine surging when the EAT ECU initiates a gear change. The ECM reduces fuelling to lower the engine torque output, thereby preventing engine surge and consequently providing a smooth gear change.