Intake Air Temperature Sensor
In the C 14 SE engine, an intake air temperature sensor (MAT sensor) is also installed. With exact determination of temperature it is possible to calculate the precise mass of the intake air. This can be used for optimizing fuel consumption and output. At the same time, exhaust emissions are reduced, as the stochiometric air/fuel ratio range can be more precisely maintained.
The temperature sensor is installed on the end of the intake manifold.
This sensor is an NTC resistor (Negative Temperature Coefficient).
That means: cold intake air temperature = high resistance
warm intake air temperature = low resistance
The relationship between the air temperature and the resistance values is demonstrated in the following table:
| Temperature [ °C] | Resistance [kW] |
|---|---|
| -40 | 100.7 |
| -20 | 28.67 |
| 0 | 9.42 |
| 5 | 7.28 |
| 10 | 5.67 |
| 15 | 4.449 |
| 20 | 3.515 |
| 30 | 2.237 |
The NTC characteristics correspond to those of the familiar coolant temperature sensor. However, the intake air temperature sensor cannot be replaced by the coolant temperature sensor.
To increase the accuracy of the sensor, the temperature is probed in two measuring ranges.
In the border range between 40 - 50 °C/104 - 122 °F, TECH 1 displays of two different voltages for one and the same temperature display are possible.