Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine background noise levels for detecting engine knock may be the basis for determining whether or not the engine is operating in a cylinder deactivation mode. Further, select variable engine displacement modes may be avoided so that engine background noise level changes may be reduced to improve engine knock detection.

Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine knock background noise levels determined during all cylinders operating mode may be applied when one or more cylinders are deactivated to determine the presence or absence of engine knock. Additionally, engine knock background noise levels determined during all cylinders operating mode may be applied when one or more cylinders are reactivated such that the engine operates with all cylinder combusting so that the possibility of indicating knock when knock is not present may be avoided.

Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Fuel injection timing and cylinder firing patterns may be adjusted to maintain engine background noise levels so that the presence or absence of engine knock may be more reliably detected. Further, select variable engine displacement modes may be avoided so that engine background noise level changes may be reduced to improve engine knock detection.

Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Fuel injection timing and cylinder firing patterns may be adjusted to maintain engine background noise levels so that the presence or absence of engine knock may be more reliably detected. Further, select variable engine displacement modes may be avoided so that engine background noise level changes may be reduced to improve engine knock detection.

Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine knock background noise levels determined during all cylinders operating mode may be applied when one or more cylinders are deactivated to determine the presence or absence of engine knock. Additionally, engine knock background noise levels determined during all cylinders operating mode may be applied when one or more cylinders are reactivated such that the engine operates with all cylinder combusting so that the possibility of indicating knock when knock is not present may be avoided.

Abstract: Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine background noise levels for detecting engine knock may be the basis for determining whether or not the engine is operating in a cylinder deactivation mode. Further, select variable engine displacement modes may be avoided so that engine background noise level changes may be reduced to improve engine knock detection.