How does a engine control unit function?
Control units have been deployed in the vehicle for over ten years now. They have been necessary to ensure adherence to modern exhaust emission standards and to make comfort functions possible.

The tasks performed by the engine control unit:
The engine control unit is like the brain and computer centre of the car. This is where all data and commands relevant for the engine come together. We regard fuel quantity and fuel injection, together with the charge air pressure, as the most important parameters.

Depending on the signals of the sensors for existing air mass, engine speed, load and further correction factors, the electronic system calculates the necessary injection time to meet the following demands: limitation of fuel consumption, reduction in pollutants contained in the exhaust gas, and an increase in specific engine output.

In addition, the unit controls a large number of further processes in the engine.  Cruise control, interfaces to other systems, fuel temperature correction, consumption display, electronic accelerator pedal, smooth running control, idle speed control, surge damping control, on-board diagnosis and also the immobilizer all run via the control unit.It is only by way of an intelligent reprogramming that a wear-free increase in power maintaining all important engine protection functions and exhaust gas values can be achieved. Depending on manner of driving and vehicle type, even a reduction in consumption is possible owing to earlier overrun fuel cut-off.

We do not offer, and never have offered additional control units, such as those that unfortunately are still being offered and give the engines false data for an increase in output. Tuning on the basis of error simulations we consider to be dubious and dangerous.


How does the engine control unit work?
Engine control consists of one or several small high-performance processors which co-ordinate and set their values for different control sequences. The microcomputer processes a program that is permanently stored (EPROM or merely a chip). The main task in the case of petrol engines is the definition of the required and max. possible injection quantity. The injection quantity depends on air intake. The air/fuel ratio must be exactly right if the catalytic converter is to work properly.

Also, the point in time must be defined at which the compressed mixture is ignited. If the ignition is delayed, consumption rises. If, on the other hand, ignition is too early, the engine starts knocking. In addition, the engine management monitors and controls many other tasks like, e.g., the automatic gentle cut-off of the injection system at a max. rpm or at top speed. A cruise control system, too can be integrated and is then controlled by the engine management. Often, control of the fan afterrun and the cold start phase depends on many different measured values, e.g. cooling-water, fuel, outside and oil temperature.

In modern diesel engines, the injection quantity defined is dependent on air mass intake, air pressure, external temperature, engine speed and load. This is necessary to meet future exhaust emission standards. Also, in the case of turbocharged vehicles, the charge air pressure of the turbo charger defined is dependent on load and engine speed and adjusted accordingly. The data required for the control are likewise stored in the EPROM. Using this three-dimensionally stored data (maps), the engine control unit controls the injection quantity, possible or required, for a certain load-speed point.


What do we optimise?
The data for the control is kept in the data storage as maps. These three-dimensional fields contain, e.g. injection pump voltage, speed and load dependence. The stored values are experience values, which have been obtained by test engineering methods using power and exhaust gas measurements. The three-dimensional maps are optimised by us on the test bench to obtain more output with low consumption and good exhaust gas values. Most engine control units are built be the Bosch firm and are deployed in different types.