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1F2 -- 60 M161 ENGINE CONTROLS DAEWOO MY_2000 HOT FILM AIR MASS (HFM) SENSOR YAA1F570 The Hot Film Air Mass (HFM) sensor with recognition of flow direction related to pulsating flow is designed for record- ing load on Engine Control Module (ECM) by measuring the output voltage proportional to the reference voltage of the ECM. Mass Air Flow Sensor Mass Air Flow (MAF) is a thermal flow meter whose sensor element with its temperature sensors and heating area is exposed to the MAF to be measured. A heating area located in the center of a thin membrane is controlled to an over-- temperature by a heating resistor and a temperature sensor of this membrane. And the value of over--temperature depends on the temperature of the in--flowing air. coming flow. With incoming flow, upstream part is cooled down but downstream temperature retains its temperature more or less due to the air heated up in the heating area. This temperature difference in quantity and direction depends on the direction of the incoming flow. intake air at a constant level. The amount of heating current required to maintain the temperature thus provides an index for the MAF. This concept automatically compensates for variations in air density, as this is one of the factors that determines the amount of warmth that the surrounding air absorbs from the heated element. MAF sensor is located between the air filter and the throttle valve. ECM uses this information to enrich the mixture, thus increasing the fuel injector on--time, to provide the correct amount of fuel. When decelerating, the mass flow decreases. This mass flow change is sensed by the MAF sensor and read by the ECM, which then decreases the fuel injector on--time due to the low fuel demand conditions. cants are used care must be taken to ensure that they do not enter the flow passage and cannot be sucked in with the air flow. |