DME Sensors

New or Modified DME Sensors and Functions

Differential Hall Sensor







The speed sensor is installed on the left behind the engine at the bottom of the transmission bell housing viewed in driving direction.







A new Hall sensor is used in the Panamera for determination of the engine speed instead of the previous inductive pick-up. In addition to detecting the engine speed and reference mark, the new multiple Hall sensor also detects the direction of rotation of the engine. This function means that the engine starting operation is very fast. The speed sensor has 3 integrated Hall sensors (A - B - C). Only 1 rotor with 60 - 2 teeth is needed on the crankshaft to generate the corresponding PWM signal.

Function - The sensor calculates two signal channels from three Hall signals.







Signal

The sensor switches "low" when the speed channel passes through the zero line. The offset between the tooth center adapted in the DME software. Detection of the direction of rotation takes place on the basis of the phase displacement between the speed channel and direction of rotation channel.







Channels 1 and 2 are needed to detect the direction of rotation:
Channel 1 = Speed channel (A - B)
Channel 2 = Direction of rotation channel (B - C)

Direction of rotation forward (upper graph) Channel 2 leads channel 1

Direction of rotation backward (lower graph) Channel 1 leads channel 2

NOTE: In the event of speed sensor failure, the engine starts with a delay, a fault is stored and the vehicle is operated with reduced engine power.

Temperature range -40 °F. (-40 °C.) to 302 °F. (150 °C.)
Engine speed range 0 to 10,000 rpm forward
0 to 3,000 rpm backward

New Pressure/Intake Temperature Sensor on the
Intake Manifold (naturally aspirated and turbo engines)







The pressure sensor detects the intake manifold pressure.
The DME control unit determines the respective air mass from different maps and the intake air temperature installed at the rear of the intake manifold (1).







Advantages of the pressure sensor:
- Increased performance thanks to dethrottling of the intake section
- Lightweight design (the pressure sensor replaces 2 MAF sensors)

The new pressure sensor on the intake manifold replaces the previous hot-film mass air flow (MAF) sensor. In order to ensure that the correct mixture composition is always present in the combustion chambers, the actual intake air mass is continuously measured using a pressure sensor for measuring the mass air flow. As a result, the correct mixture is always available in the combustion chambers, and any changes in the atmospheric pressure (due to changes in altitude) and outside temperature are compensated. This new pressure sensor replaces the hot-film mass air flow measurement system used in the past and also contributes to increased performance by dethrottling the intake section.

The integrated temperature sensor measures the intake air temperature on both naturally aspirated and turbo engines. The load signal of the pressure sensor and the intake air temperature can be found under the DME actual values.

Design and Signal

The cross section and design of the pressure sensor.







The voltage characteristic as a function of the intake manifold pressure are shown in the following graph.







Supply voltage = 5 V
Uout - Output voltage (V)
US - Pabs - Absolute pressure (kPa)

The plausibility check for the pressure sensor signal is performed in the DME control unit. For this purpose, the current filtered values of the ambient pressure sensor (in the DME control unit) and intake manifold pressure sensor (and boost pressure sensor: Turbo only) are compared with each other in the event of ignition On more than 10 seconds or control unit run-on more than 10 seconds, for example. Further diagnostic information is described in Guided Fault Finding.