Patent ID: 7707977
Filing Date: 2010-05-04
Classification: F01L,F02D,Y02T

Abstract:
1. A method for operating a multi-cylinder internal combustion engine comprising the steps of: moving engine valves of the engine between an open position and a closed position at least in part by rotating a cam; activating a diagnostic routine; varying the opening or closing of the engine valves while the diagnostic routine is activated, the engine valves including intake or exhaust valves, in fluid communication with each of the cylinders of the engine; wherein the varying step includes outputting control commands to valve actuators of the engine; monitoring an acceleration parameter of the engine after outputting the control commands; comparing the monitored acceleration parameter of the engine with an expected acceleration of the engine; and generating a signal indicative of engine valve performance status in response to the comparison of the monitored acceleration parameter of the engine with an expected acceleration of the engine, wherein the signal is further indicative of whether a difference between the monitored acceleration parameter and the expected acceleration satisfies fault criteria.