Intake Air Temperature

Intake Air Temperature Sensor

The intake air temperature sensor is integrated in the mass air flow sensor while on the M52, M54 and M56 engines it is screwed into the air intake manifold. A precision ballast resistor (NTC resistor) is used to convert the temperature into a measurement value which can be evaluated electrically by the DME control module.

The intake air temperature sensor is not required for correction of the injection timing as the intake air temperature is automatically taken into consideration in the air mass measuring procedure. The intake air temperature sensor is required for the start procedure in conjunction with the engine coolant temperature sensor. The resistance values of both sensors supply exact information for calculating the injection timing. In this way hot start problems in particular are avoided.

The air column in the mass air flow sensor can oscillate during the start procedure. For this reason, the value output by the mass air flow sensor cannot be used as a correct value for injection timing.

During the start procedure, the temperature sensors are therefore used as a measured variable up to a freely programmable engine speed threshold.