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A heat-sensing type air flow sensor has been adopted. In contrast to the Karman vortex
air flow sensor, which detects the volumetric flow rate of air, this type utilizes the flow
speed dependence characteristics of heat transmission to detect the mass flow rate of air, converts
it into an amperage, and outputs it to the Engine-A/T-ECU.
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The sensing portion consists of an ultra-compact, heat-sensing membrane resistor. The
Engine-A/T-ECU regulates the amperage in order to maintain a constant temperature in the heat-sensing
resistor. When the mass flow rate of air increases, the heat transmission from the heat-sensing
resistor to the air also increases. Therefore, the amperage that is regulated by the Engine-A/T-ECU
increases. Because the heat transmission rate and the amperage are proportionate, the Engine-A/T-ECU
is able to measure the air flow rate based on the amperage. The use of the ultra-compact membrane resistor,
which provides the same high-speed response as the Karman vortex air flow sensor, enabled the
compact and lightweight sensor to be installed in the air intake hose.
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| BAROMETRIC PRESSURE SENSOR
This sensor has been changed to a type that is built into the Engine-A/T-ECU.
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The throttle position sensor, which is located in the throttle body, outputs a voltage
signal, which corresponds to the rotational angle of the throttle shaft, to the Engine-A/T-ECU.
In accordance with this signal, the Engine-A/T-ECUeffects feedback control of the throttle valve
control servo. This throttle position sensor uses a non-contact Hall IC to enhance its reliability.
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The throttle position consists of a permanent magnet fixed to the throttle shaft, a Hall
IC that outputs electrical voltage in accordance with the magnetic flux density, and a stator
that effectively guides the magnetic flux from the permanent magnet into the Hall IC.
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The magnetic flux density that passes into the Hall IC when the throttle valve is fully
closed in kept to a maximum in the above direction on this paper.
As the result of this, the electrical voltage is minimal output.
The magnetic flux density is zero when the throttle valve is half opened.
The magnetic flux density that passes into the Hall IC when the throttle valve is fully
opened is kept to maximum in the below direction on this paper.
As the result of this, the electrical voltage is maximal output.
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The throttle position sensor outputs through two systems (main and sub). This improves
the accuracy of the system to detect malfunctions and reinforces the failsafe function in order
to ensure reliability.
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