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Engine Control Module: Description and Operation



Motronic Control Unit ME 7.8.1







The further-developed Motronic control unit ME 7.8.1 is used worldwide. It is based on the ME 7.8 of the 911 Turbo (996) and the further development of the current 911 generation. The new Motronic control unit features a processor speed of 40 MHz with a memory capacity of 1 MB.

The Motronic ME 7.8.1 control unit has been adapted to the engine-specific requirements of the following components and systems:
- Improved lower pollutant emissions and monitoring by the On-Board Diagnostics system (OBD), which informs the driver via a warning in the instrument cluster when emission and engine-related faults arise.
- Diagnosis of the DME control unit via CAN.
- Control of turbocharger with variable turbine geometry.
- Exhaust temperature control by way of additional temperature sensors in the turbine housing (left and right) in order to protect the variable turbine geometry components.
- Control of Overboost function in conjunction with the "Sport Chrono Package Turbo" option.
- Continuous camshaft adjustment of the intake camshafts.
- Valve lift switchover "VarioCam Plus".
- Worldwide stereo lambda control with LSU broadband oxygen sensors upstream of the catalytic converter and LSF step oxygen sensors downstream of the catalytic converter.
- Oxygen sensor heating.
- Sequential fuel injection with new EV-14 injection valves.
- Electronic accelerator pedal unit.
- Electronic throttle adjusting unit (electronic throttle).
- Load detection with 2 pipe hot-film mass air flow sensors HFM 5-6.4.
- Sport Chrono Package Plus (Turbo).
- Cylinder-specific knock control.
- Static high-voltage system with individual ignition coils.
- One three-way catalytic converter per cylinder bank as the main catalytic converter.
- Secondary air control.
- DM-TL fuel tank leakage check using excess pressure (USA).
- Stepless activation of the electric radiator fans in the front end.
- 2-speed engine compartment scavenging blower.
- Air conditioning compressor control.

Data Records

The following data records are available for programming the DME control unit 7.8.1: 997 TOP; MT (manual transmission); AT (Tiptronic S); EU2; EU4; Japan and LEV.

Input Signals Of The Motronic Control Unit ME 7.8.1

- Power supply terminal 15, terminal 30, terminal 87 and ground.
- Engine speed sender.
- Hall sensor - intake camshaft, bank 1 and bank 2.
- Electronic accelerator pedal unit with pedal sensor 1 and 2.
- Throttle potentiometers 1 and 2 (in the electronic throttle).
- 2 hot-film mass air flow meters HFM 5-6.4 (load signal).
- Position of boost pressure adjusters.
- Turbocharger temperature.
- Pressure upstream of throttle.
- Air temperature upstream of throttle.
- Coolant temperature sensor (NTC).
- Knock sensor, bank 1 and bank 2.
- LSU broadband oxygen sensors upstream of the catalytic converter, bank 1 and bank 2.
- LSF step oxygen sensors downstream of the catalytic converter, bank 1 and bank 2.
- Oil temperature.
- Oil pressure.
- Engine compartment temperature sensor (NTC).
- Coolant level switch.
- Rear lid switch.
- Bit-synchronous connection to generator regulator.
- Tank leakage diagnostics module DM-TL (USA only).
- Start enabling: MT: clutch switch low, AT: P/N switch.
- Crash signal (PWM) from airbag control unit.
- CAN information.
- Brake light switch (CAN signal).
- Clutch pedal switch high (CAN signal).
- Fuel level (CAN signal).
- Vehicle speed (CAN signal).
- Air-conditioning demand (CAN signal).
- Immobilizer (CAN signal).
- Sport Chrono button (Turbo) (CAN signal).

Drive Links Of The Motronic Control Unit ME 7.8.1

- Starter controller.
- Fuel pumps 1 and 2.
- Injection valves for cylinders 1 to 6.
- Individual ignition coils for cylinders 1 to 6.
- Throttle adjuster (electronic throttle).
- Boost pressure adjusters 1 and 2.
- Valve for intake camshaft adjuster, bank 1 and bank 2.
- Valves for valve lift switchover 1 and 2.
- Tank ventilation valve.
- Turbo diverter valve.
- Tank leakage diagnostics module DM-TL (USA only).
- Oxygen sensor heating.
- Secondary air pump.
- Cooling water fan (via additional control unit), CAN signal.
- Engine compartment scavenging blower speeds 1 and 2 via relay.
- Air conditioning compressor relay.
- Check Engine light (CAN signal).
- Electric water pump (direct).

Electronic Accelerator Pedal Unit

The 911 Turbo (997) is provided with an electronic accelerator pedal unit from the current 911 (997) series.

DME Power Supply

The power supply of the DME control unit is the same as in the current 911 (997) series. The assignment of the fuse carrier, as well as relay carriers 1 and 2, can be found in the circuit diagram on the PIWIS Tester.

Starting The Engine

In order to start the engine it is necessary, after the ignition key has been identified, to fully depress the clutch pedal (vehicles with manual gearbox) or the brake pedal (Tiptronic vehicles). In Tiptronic vehicles, the selector lever must additionally be set to either "P" or "N".

CAN Networking

As in current (987/997) models, electronic networking in the new 911 Turbo facilitates the exchange of data and electronic information between the various control units throughout the vehicle via the internal high-speed network, the CAN bus (Controller Area Network).

CAN Communication For The Motronic Control Unit (DME)

On the 911 Turbo (997), diagnosis of the DME control unit is performed for the first time via CAN.

The DME control unit communicates with the following control units via CAN:
- Gateway control unit
- Driver authorization control unit
- Tiptronic control unit
- PSM control unit
- PTM control unit
- Steering angle sensor
- Yaw velocity sensor
- Airbag control unit
- Air conditioning control unit
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