Systems and methods for adjusting ignition timing to one or more cylinders of a variable displacement engine responsive to a knock indication are described herein. In one particular example, during a partial cylinder mode, ignition timing to one or more cylinders may be adjusted responsive to a knock indication based on the number of cylinders deactivated; whereas during the full cylinder mode, ignition timing for all cylinders are adjusted responsive to a knock indication. Thereby, the systems and methods described allow a larger partial cylinder operating window that has a benefit of enhancing a vehicle's fuel economy.