Engine Control Module: Description and Operation
GF07.61-P-6000V ME-SFI [ME] Control Unit, Component Description
Location
The ME 9.7 control unit is located on the intake manifold supporting the engine.
Task
Controls in line with the input signals the functions of:
- Ignition system/fuel injection system
- Electronic accelerator/cruise control/idle speed control
- Diagnosis/fault storage
- Drive authorization system/immobilizer
Design
Connection is achieved on the engine-side and on-board via two couplings interlocked via slide valves. Cooling fins on the upper side provide the necessary rejection of heat. Vibrations are suppressed by rubber brackets.
Function
Control of fuel injection system
The ME control unit actuates the fuel injection valves separately corresponding to the firing order (sequentially) according to the input signals and the performance maps stored in the ME control unit. The ME-SFI control unit calculates the opening times (injection times) of the fuel injection valves.
Control of ignition system
The ME-SFI [ME] control unit actuates the ignition system according to the input signals and performance maps stored in the ME-SFI [ME] control unit. The ME-SFI control unit calculates the ignition angle values and controls the anti-knock control (AKC).
Control of idle speed control
The throttle valve actuator is actuated on the basis of the input signals and the performance maps stored in the ME control unit.
Control of cruise control
The ME control unit operates the throttle valve actuator for the cruise control function on the basis of the input signals and the position of the cruise control switch.
Additional cruise control functions include variable speed limiter and Distronic.
Diagnosis/DTC memory
The ME-SFI control unit checks its inputs and outputs for plausibility and recognizes possible faults. The following faults can be distinguished:
- Faults present all the time
- Loose contact faults that have occurred while driving
The faults are erased in the ME-SFI control unit after circuit 30 is interrupted.
Drive authorization system/immobilizer
The ME-SFI control unit is always equipped with an immobilizer. When the vehicle is locked, the drive authorization system control unit transmits information over the CAN data bus to the ME-SFI control unit, which thereupon interlocks the engine management system (fuel injection system). The engine can be started (start enable) only when the vehicle is unlocked with the authorized key again and the control unit of the drive authorization system sends information to this effect to the ME-SFI [ME] control unit via the CAN data bus.
The ME control unit is functional only with a CAN data bus and the FBS 3 drive authorization system.
Engine speed signal
The ME control unit generates the short-circuit proof engine speed signal TNA from the signals supplied by the crankshaft position sensor, and outputs them to other control units. 3 pulses are output per engine revolution.
Actuations with STAR DIAGNOSIS
Functions can be actuated specifically for diagnostic purposes. These are listed in a menu item.
Variant coding
For adapting the ME control unit to different vehicle versions and vehicle equipment by means of matching code numbers. Coding is performed with STAR DIAGNOSIS. The variant coding can be used to code the following vehicle versions and equipment variants:
- Vehicle model
- National version
- Transmission version
- with or without TWC
Fuel consumption signal
The consumption signal is calculated from the injection times (e.g. 8 liters/hour) and is transmitted via CAN to the trip computer in the instrument cluster.
Start recognition
The engine control unit is informed about the introduced starting procedure via the CAN message "circuit 50". This is necessary in order, for example, to trigger the start quantity control, the starter control, the post-start enrichment and the ignition timing when starting.
Computer run-on
After the ignition is switched off, the ME-SFI control unit performs a delayed-off run during which certain data memories are updated (e.g. the DTC memory). The run-on time with a warmed up engine is approx. 5 s, but may be extended to several minutes by various functions. After the fault memory has been cleared, the run-on time must expire.
Various engine operating information is transmitted via the CAN databus from the ME control unit to the instrument cluster and to other control units which are connected to the CAN databus.