Engine Management System

By Greg Vernon

The Engine Management System, which can be also known as the Engine Control Unit or ECU, essentially controls all aspects of an internal combustion engine.

Most manufacturers install a preprogrammed system into their engines. These programmable chips are often required when extensive aftermarket changes are made to an engine which drastically alters engine performance. For example, adding a turbo kit would require a new, programmable, engine control unit.

Replacing a pre-installed Engine Management System, with a programmable one can make solving engine problems easier. For example, if your car is running rich or lean switching to a programmable Engine Management System, will allow a technician to change the amount of fuel that is burned. In the same process, the technician can also determine the exact amount of fuel to be sent to cylinders based on every throttle position and engine RPM, giving your car a perfectly tuned engine. A properly tuned car performs better and achieves better fuel efficiency.

Many other areas of the engine may be controlled by properly programming an engine management unit. For example, users can program a rev limit, which specifies the maximum RPM the engine can achieve before either cutting fuel or the ignition is cut. Additionally, the ignition can be programmed to define when the spark plug should fire.

There are also programmable Engine Management Systems designed specifically for racing applications. Racing ECUs are far more advanced – and expensive – than the typical Engine Management System but offer expanded features required for racing. One of the features found in a racing Engine Management System is launch control. This limits the power available to the engine in first gear to reduce the risk of a burnout.

Most racing ECUs are also equipped with a simple data logger, which can store 16 megabytes of race data. The data logger captures all engine events such as misfires, stalls, and other anomalies harmful to engine performance. This data can then be analyzed by engine technicians with special software on a personal computer and adjustments to the engine can be made.

Often these racing ECUs require special data-stacks to display information such as speed and rpm to the driver. Typically, these stacks are digital and communicate with the Engine Management System, via proprietary protocols over RS232 or CANbus connections.

It is also possible, on certain modern automobiles to change the factory installed Engine Management System, programming via the OBD port. This means you can retain all factory stock features as well as reducing cost by using wiring already built into the engine. Usually, very little hardware adjustment is needed but in order to change the programming, you will need specialized equipment and software.

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