Engine Control Module: Description and Operation
DME Control Unit EMS SDI 3.1
NOTE: The DME control unit can be programmed with the data records for the various Carrera and Carrera S models on a country-specific basis.
A completely new DME control unit EMS SDI 3.1 developed by Continental is used for the DFI flat-six engines. It is designed specifically to meet the requirements for the use of direct fuel injection. Compared to the previously used Bosch ME 7.8 DME control unit, the EMS SDI 3.1 DFI control unit features greater processing power with triple the clock speed and approx. 65% more memory capacity. The special demands for the use of direct fuel injection require significantly more functions and faster data processing. It is particularly injector control during multiple injection and the comprehensive data maps that require great computing power.
A voltage of approx. 75 volts is required to open the DFI high-pressure fuel injectors. This requires 12-to-75 volt DC/DC converters, which are installed in the DME control unit. Some areas on the housings of these voltage converters become very hot. This heat is dissipated via the aluminium cover.
The DME control unit features the following key functions:
- Direct fuel injection (DFI) control
- Control of the DFI fuel injectors
- Control of the flow control valve for high-pressure control
- Control of the demand-controlled oil pump
- Communication with the optional Porsche Doppelkupplung transmission (PDK)
- Communication with the PSM
- Communication with the optional PTM
- Control of the shift indicator
NOTE: Further information about the corresponding systems can be found in the following modules of this Technical Service Information.
1 Engine
3 Transmission
4 Chassis
9 Electrics and Electronics
The DME control unit receives input signals from the following sensors:
- Speed sender (engine speed and crankshaft reference mark)
- 2 hall-effect sensors (intake-camshaft position measurement)
- Hot-film air flow sensor (engine-load signal)
- Electronic throttle module (torque-demand measurement)
- Throttle angle (throttle plate position measurement)
- 2 knock sensors (for cylinder-selective knock control)
- 2 LSU broad-band oxygen sensors ahead of the catalytic converters (for stereo oxygen sensor closed-loop control)
- 2 LSF step oxygen sensors behind the catalytic converters (for catalytic converter monitoring)
- Temperatures (cooling water, intake air, engine oil, ambient temperature)
- Vehicle speed
- Air conditioning performance
- Fuel pressure (measurement of the fuel high pressure)
- Oil pressure
- Ambient pressure
CAN
The DME control unit receives information about the following via the CAN interface:
- Vehicle dynamics control
- Transmission control
- Engine immobilizer
- Instrument cluster
- Air conditioning control
The DME control unit controls the following actuators:
- 6 ignition modules (individual ignition coils with integral driver)
- 6 fuel injectors (high-pressure fuel injectors)
- Control unit for fuel pump (for demand control of the in-tank fuel pump, low-pressure side)
- Flow control valve (for flow control on the fuel high-pressure side)
- Throttle actuator control (adjustment by electronic throttle from idle speed to wide open throttle)
- 4 oxygen sensor heaters
- 2 camshaft position control actuators (adjustment of the intake camshafts)
- 2 valve-lift actuators (to change the valve lift of the intake camshafts)
- Tank vent valve
- Continuous engine-fan control
- Starter control
- Oil-pressure control (demand oriented)
- Switching valve for tuning flap (Carrera S)
- OBD lamp (for monitoring the emission control system)
Other functions of the DME control unit
Control of VarioCam Plus
The new DFI flat-six engines retain the proven VarioCam Plus technology from the predecessor model. In addition to intake-camshaft adjustment (0 to 40° crank angle), this system also allows valve-lift adjustment of the intake camshaft (from 3.6 mm to 10.5 mm for the 3.6-liter engine or 11 mm for the 3.8-liter engine). Besides the best possible running quality, favourable fuel consumption and low pollutant emissions, this above all ensures high power and torque values in combination with the appropriate intake system.
Variable oil pump
The DME control unit is responsible for the demand-controlled operation of the variable oil pump, while adjustment is performed hydraulically. The engine management system uses the input values for engine speed, temperature and torque. Based on this information, the engaged gear wheel width and therefore the geometric displacement volume of the gear wheel set is changed through the axial movement of a gear wheel (moved hydraulically) and this in turn changes the delivery quantity and the oil pressure. The pump ensures that only the pumping work required for the relevant load range of the engine is demanded. This reduces the energy consumption of the oil pump to a minimum and also ensures demand-controlled lubrication.
Control of electric radiator fans
The DME control unit also activates the drivers for the electric radiator fans in order to achieve infinitely adjustable control.
Communication with control unit
Porsche Doppelkupplung transmission (PDK)
The complex co-ordination between the engine and the optional Porsche Doppelkupplung transmission also requires a highly dynamic, powerful engine control unit. Only these parameters allow high performance and low fuel-consumption values and exhaust emissions to be ensured.