Method and system for estimating and reducing engine auto-ignition and knock

A control system for an engine includes a heat-release rate (HRR) module, a first filter module, a second filter module, an auto-ignition energy determination module, and a corrective action module. The HRR module generates an HRR signal based on in-cylinder pressures of a cylinder of the engine. The first filter module generates a first filtered HRR signal indicative of a first HRR due to combustion in the cylinder by filtering the HRR signal. The second filter module generates a second filtered HRR signal indicative of a second HRR due to auto-ignition in the cylinder by filtering one of the HRR signal and the first filtered HRR signal. The auto-ignition energy determination module determines an auto-ignition energy of the cylinder based on the first and second filtered HRR signals. The corrective action module selectively adjusts auto-ignition of the engine based on the auto-ignition energy. A related method is also provided.