Motronic ME 7.8
Motronic ME 7.8
2470 Motronic Control Module
The 911 Carrera and 911 Carrera S are equipped with the familiar Motronic ME 7.8 engine control system. Innovations here include increased computing power and greater memory capacity. These enhancements are required on the new models to ensure the enhanced OBD scopes and to facilitate the Sport Chrono function.
Enhancement of On-Board Diagnostics OBD (USA) and EOBD
The familiar On-Board Diagnostics system (OBD -> USA) or the European On-Board Diagnostics system (EOBD -> Europe/RoW) for emission monitoring is also used on the 911 Carrera and 911 Carrera S models. This system is designed to warn drivers anywhere in the world, via an appropriate signal in the instrument cluster, of any emission- or engine-related faults.
Each system is fully compliant with all world-wide governmental regulations.
- Check engine light is on - emission-related fault
- Check engine light is flashing - fault causing damage to catalytic converter
There will also be an enhancement to the On-Board Diagnostics systems worldwide for the model year 2005. Any occuring faults with additional information displays are stored in the fault memory of the Motronic control module and can be read out with the PIWIS Tester.
The additional scopes required specifically for California include:
- More complex sensor diagnostics.
The operating range and plausibility of emission-related sensor signals such as ambient pressure, oil temperature, ambient temperature, etc. must be verified.
- Increased number of fault paths.
Each fault type of a signal fault must be stored in a separate fault path.
- Enhanced field monitoring of the vehicle fleet.
The function and fault management systems of the diagnostics system on standard production vehicles must be tested and documented every year.
The Motronic ME 7.8 control module was adapted to the engine specific requirements of the following components and systems:
- Electronic accelerator pedal (electronic throttle)
- Sequential fuel injection
- Cylinder-specific knock control
- Static high-voltage system with individual ignition coils
- Load measurement using hot film mass air flow sensor (HFM 5 CL)
- Two-stage resonance intake system
- Stereo oxygen sensor closed-loop control
- Oxygen sensor heating
- 2 three-way catalytic converters
- Secondary air control
- Fuel tank leakage check using excess pressure (USA)
- Continuous camshaft position adjustment using vane cell adjuster
- "VarioCam Plus" valve lift control
- Force coordination for Tiptronic and PSM
- On-Board Diagnostics system for monitoring emission control system (OBD II and EOBD)
- Infinitely variable activation of the electronic radiator fans
- Engine compartment scavenging blower
- Air conditioning compressor control
- Cruise control function (via electronic throttle)
- Rear spoiler activation (dependent on vehicle speed and engine compartment temperature)
- Sport Chrono Package Plus (optional)
The following input signals are available to the Motronic control module:
- Power supply terminal 15, terminal 30, terminal 87 and ground
- Engine speed senders
- Hall sender inlet camshaft, bank 1 & bank 2
- Hot film mass air flow sensor HFM 5 (load signal and intake air temperature)
- Coolant temperature sensor (NTC) knock sensor, bank 1 & bank 2
- Oxygen sensors LSF in front of catalytic converter, bank 1 & bank 2
- Oxygen sensors LSF behind catalytic converter, bank 1 & bank 2
- Pedal sensor potentiometers 1 & 2 (in accelerator pedal unit)
- Throttle potentiometers 1 & 2 (in the electronic throttle)
- Oil temperature and oil level
- Oil pressure sensor
- Engine compartment temperature sensor (NTC)
- Tank leakage diagnostics module DM-TL (USA only)
- CAN information
- Brake light switch
- Clutch pedal switch
- Fuel level
The Motronic control module activates the following outputs:
- Starter relay
- Fuel pump relay
- Injection valves for cylinders 1 to 6
- Individual ignition coils for cylinders 1 to 6
- Throttle position adjuster (electronic throttle)
- Cruise control (Speed Adjustment System SAS)
- Oxygen sensor heating
- Valve for intake camshaft adjuster, bank 1 and bank 2
- Valve for valve lift switchover, bank 1 and bank 2
- Switching valve for tuning flap
- Tank vent valve
- Tank leakage diagnostics module DM-TL (USA only)
- Secondary air pump
- Cooling water fan right and left (via auxiliary control module)
- Engine compartment scavenging blower
- Cooling water shutoff valve (Tiptronic only)
- Air conditioning compressor relay
Effects of the Sport Chrono function on the Motronic
The optionally available Sport Chrono Package notably increases driving pleasure and the vehicle's performance. The engine is also affected when the Sport Chrono button is activated.
The following features are initiated:
Sportier load cycle properties.
After pressing the Sport button, Sport mode is indicated by a symbol on the middle display of the instrument cluster.
When the Sport Chrono function is selected, the transfers between acceleration and deceleration become sportier. This means that injection and ignition are switched on and off more directly when accelerating and particularly when decelerating, resulting in a more spontaneous and dynamic load cycle.
More abrupt engine speed cut-off.
To increase driving comfort a 'gentle' cut-off is generally used when accelerating and reaching the engine speed cut-off setting. In the process the throttle is continuously closed when approaching the engine speed cut-off level.
The Sport Chrono function facilitates additional acceleration potential through the use of an abrupt engine speed cut-off by switching off individual cylinders (injection and ignition) in a rotating fashion just shortly before the engine speed limit. The perceptible limit of acceleration lets the driver know if an upshift is executed too late. This allows the driver to learn how to identify the optimum shift point with more accuracy and to take fuller advantage of the engine s potential for acceleration. When the Sport Chrono button is pressed, the abrupt cut-off is active in 1st to 5th gears for the manual gearbox (without Sport Chrono function only in 1st and 2nd gears) and in the manual gate "M" for Tiptronic transmission.
More dynamic accelerator pedal characteristic.
The electronic accelerator pedal (electronic throttle) has been used on the 911 Carrera (996) models since model year 2001. With this system, the accelerator pedal position is converted into electrical signals via potentiometers and forwarded as a control signal to the electromechanical throttle via the Motronic control module. The conversion between accelerator pedal angle and throttle angle is performed in the Motronic control module. Sensitivity and therefore driveability in the lower speed and load range are factors here, as well as across the entire throttle pedal travel range.
NOTE: Details concerning the function of the entire Sport Chrono Package Plus can be found in of this Technical Service Information.
When the Sport Chrono button is active, a more dynamic accelerator pedal characteristic produces a more spontaneous engine response, enhancing the sporty character. This is achieved via a steeper rise for the electronic throttle characteristic by means of a shorter conversion between accelerator pedal and throttle angle. This means that the throttle is opened further or faster with the same accelerator pedal travel and selected Sport Chrono function (with Tiptronic S only in the manual "M" position).