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Functional description

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An electrically heated measuring cell protrudes into the air flow. The temperature of the measuring cell is always kept constant. The air flow draws heat from the measuring cell. The greater the air mass flow the more energy must be deployed to keep the temperature of the measuring cell constant.

The characteristic curve of the hot film air mass meter is extended in the negative value range of the air mass flow (range greater than 550 μs). Pulsations due to the uneven firing interval on a bank also mean that negative air mass flows occur during driving. These negative air mass flows are included in the calculation.

Fig 1: Identifying Hot Film Air Mass Meter Components
G09909131Courtesy of BMW OF NORTH AMERICA, INC.
Item Explanation
1 Hot film air mass meter
2 five-pin plug connection
3 Intake silencer