V70 2.4 L5-2.4L VIN 61 B5244S (2001)
Air Flow Meter/Sensor: Description and Operation
Mass Air Flow (MAF) Sensor
The mass air flow (MAF) sensor gauges the air mass sucked into the engine. It continuously transmits signals to the engine control module (ECM) about
the mass of the intake air. This data is used by the engine control module (ECM) to calculate:
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the injection period
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the ignition timing
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the engine load.
The transmission control module (TCM) also uses this data for its gear shift calculations. This data is transmitted to the transmission control module
(TCM) from the engine control module (ECM) via the high speed side of the Controller area network (CAN).
The mass air flow (MAF) sensor is a hot wire type. Unlike other hot wire types, the mass air flow sensor in the Denso system uses a hot wire which has a
ceramic casing. This eliminates the need for a clean burn function.
The mass air flow (MAF) sensor is supplied with battery voltage by the system relay and is grounded in the engine control module (ECM). The signal
from the sensor is analog and varies between 0.5-4.5 V depending on the air mass. Low air flow (low mass) results in low voltage, high air flow (high
mass) gives high voltage.
The mass air flow (MAF) sensor is positioned between the air cleaner (ACL) housing and the intake manifold.
The mass air flow (MAF) sensor also contains an intake air temperature (IAT) sensor.
The engine control module (ECM) can diagnose the mass air flow (MAF) sensor. The signal can be read using VADIS.
