V70R AWD L5-2.3L Turbo VIN 52 B5234T6 (1998)
Air Flow Meter/Sensor: Description and Operation
MASS AIR FLOW SENSOR
The Mass Air Flow (MAF) Sensor supplies the Engine Control Module (ECM) with a signal describing the intake air mass.
This information is used to calculate:
Injection period
^ Ignition timing
^ If the engine coolant fan needs to run-on.
The mass air flow (MAF) sensor consists of a plastic housing containing a connector, electronic circuitry and an aluminum heat sink. The mass airflow
(MAF) sensor measuring device is a heated film mounted in a pipe which is cooled by the intake air to the engine. The heated film consists of four
resistors:
The mass air flow (MAF) sensor is supplied with battery voltage and has separate power and signal ground points. The signal from the sensor varies
from 0 V to 5 V depending on the mass of air passing. Voltage increases with air flow.
Since working temperature is relatively high (170°C), and the flow and temperature sensitive resistors are mounted on the side of the hot film, a
burn-off function is not required.
The engine control module (ECM) will adopt substitute values if the mass air flow (MAF) sensor signal is missing or faulty.
The mass air flow (MAF) sensor is located between the Air Cleaner (ACL) cover and the fresh air intake.
