Detection of Coking in the Intake Tract of an Internal Combustion Engine

摘要

A method for detecting coking in the intake tract of an internal combustion engine having direct fuel injection is provided. The internal combustion engine has variable intake valve control. The variable intake valve control makes it possible to change the open time of the intake valves in relation to the crank angle of the crankshaft. In the method, the internal combustion engine is operated in idling mode at an idling rotational speed that is elevated in comparison with the normal idling operation. In order to perform the measurement, the open time of the intake valves is also shifted in an advanced direction. An uneven-running characteristic value of the internal combustion engine that is characteristic of the uneven running of the internal combustion engine is determined, and the presence of coking in the intake tract can be detected on the basis of the uneven-running characteristic value.

主权项

1. A method for detecting coking in an intake tract of an internal combustion engine having direct fuel injection and variable intake valve control, the method comprising the acts of:
operating the internal combustion engine in idle at an idle speed that is increased compared to normal idle operation; controlling an opening time of the intake valves to achieve an early timing event; and determining a rough running characteristic of the internal combustion engine which is typical of rough operation of the internal combustion engine, wherein presence of coking in the intake tract is detectable based on the determined rough running characteristic.