Methods and systems are provided for determining a status of an air filter in an intake of an engine in a hybrid vehicle. One example method includes, during an engine-off condition, utilizing a pump in an evaporative leak check module of the hybrid vehicle to produce a pressure in an intake manifold of the engine, and indicating degradation of the air filter based on a comparison of barometric pressure and the pressure produced in the intake manifold. In this way, degradation of the air filter may be determined without engine operation.

In one example embodiment, an engine flow measurement device features an engine data repository, one or more sensor units, and a measurement unit. The measurement system is configured to identify, from performance data, a maneuver performed during operation of the aircraft and to measure, for the identified maneuver, a plurality of maneuver flow values achieved during performance of the maneuver. The plurality of maneuver flow values correspond to a plurality of maneuver engine power values. Each of the plurality of maneuver flow values represent a volume of air flow through the air filter at a particular moment during performance of the maneuver.

A filter system for intake air of an internal combustion engine has a housing with a cover. A filter element is arranged in the housing. An inlet feeds a medium to be filtered into the housing and an outlet discharges the medium from the housing. The filter element has a filter body with first end face and opposite second end face. The filter element has an open first end plate at the first end face and a second end plate at the second end face. A support tube is arranged concentrically about a longitudinal axis in the housing and attached with a first end to the housing. The support tube is arranged in the interior of the filter element and radially supports the filter body. The second end plate rests on the second end of the support tube and on an inner cover contour of the cover with anti-rotation action.

An internal combustion engine monitoring system can include a fluid filter disposed between at least one fluid inlet of the internal combustion engine and at least one of a fluid source or an ambient fluid environment. At least one fluid sensor arranged can be arranged to detect a plurality of indications of respective fluid pressures on first and second sides of the fluid filter at a plurality of corresponding engine operating conditions. The indications can be compared with their corresponding operating conditions to assess a condition of the fluid filter and estimate a lifetime thereof.

An internal combustion engine monitoring system can include a fluid filter disposed between at least one fluid inlet of the internal combustion engine and at least one of a fluid source or an ambient fluid environment. At least one fluid sensor arranged can be arranged to detect a plurality of indications of respective fluid pressures on first and second sides of the fluid filter at a plurality of corresponding engine operating conditions. The indications can be compared with their corresponding operating conditions to assess a condition of the fluid filter and estimate a lifetime thereof.