300E 4MATIC (124.230) L6-3.0L (103.985) (1990)
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Air Flow Meter/Sensor: Description and Operation
Air Flow Sensor
Airflow Sensor Arrangement
The air flow sensor is mounted in the intake air stream between the air cleaner and throttle plate valve. The unit consists of an air flow sensor plate,
venturi funnel, and a sensor plate position sensor. The air flow sensor plate is mechanically connected to the control plunger in the fuel distributor,
causing the plunger to rise and fall in direct relation to the amount of air entering the engine.
Air Flow Funnel Principle
Air/fuel mixtures are also tailored to engine operating conditions by the venturi shape of the cone in which the air flow sensor plate operates. At idle,
when air flow volume is relatively low, the cone shape increases pressure above the sensor plate, providing additional force to richen air/fuel mixtures.
At part throttle the cone design causes the sensor plate to float higher than air flow through a straight sided cone would dictate, providing leaner mixtures
for improved economy. During full throttle operation the venturi shape increases air velocity, providing additional force on the sensor plate and richer
air/fuel mixtures for maximum power output.
