TMap Sensor (MINI COOPER S)
On the MINI COOPER S the pressure differential is measured across the supercharger to determine the manifold air density.
To measure this differential two sensors are fitted, one on either side of the supercharger.
A TMAP sensor is fitted on the intake manifold pressure side (after the supercharger) and has the same function as the TMAP on the MINI COOPER. The difference is that this sensor has a maximum pressure range of 250 Kpa (36.25943psi) .
Another TMAP sensor is fitted upstream of the supercharger and measures the pressure between the supercharger and throttle plate. This sensor is exactly the same part as the MINI COOPER TMAP but the temperature sensing capability is not utilized.
The TMAP sensor is located in the intake manifold where it is exposed to higher than atmospheric pressures as produced by the supercharger. The MAP sensor is located between the supercharger and the EDR, a location not effected by additional pressures from the supercharger.
The first job of the MAP sensor is the measurement of the barometric pressure. When the ignition key is placed in the "ON" position (Main Relay powered up), the sensor reads atmospheric pressure (High Voltage) because the pistons are not moving yet.
Second, it measures the absolute pressure in the intake manifold. Absolute pressure is barometric pressure minus the vacuum created by the pistons. So, if the barometer is reading 1.5 Bar at sea level and the manifold vacuum (gauge) is 1.0 Bar at idle, the manifold absolute pressure would be .5 Bar.
The EMS2000 compares the voltage from the TMAP sensor (ahead of the supercharger) to the voltage received from the TMAP (after the supercharger) and calculates air volume drawn into the engine.
- Voltage Reading of .6-1.5 volts indicates high vacuum condition (Idle or no load)
- Voltage Reading of 4 volts indicates low vacuum condition (Full Throttle)