Page 325 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

MODULE 16 : Engine Management System

LESSON 98 - 103 : Engine management system Definition,

Function, Types of system available

Objectives

At the end of this lesson you shall be able to
• define engine management system
• explain functions and types of engine management system.

Engine management system

• Definition - The engine management system is the arrangement of the devices for controlling a vehicle’s
engine.
If the car is stolen, the unit will block the vehicle’s engine management system and prevent the engine being
restarted.
The engine management system shuts down four of the eight cylinders when the power isn’t needed.
The engine management system gets the timing and fuel ratios correct for every eventuality.
Engine Management System (EMS) comprises of Electronic Control Unit (ECU), sensors, actuators and
control algorithms that determine the performance of the Engine as a whole and as part of the vehicle.
The Electronic Control Unit consist of t microprocessor with peripheral devices like ignition driver, ADCs device
and I/O drivers. Microprocessor controls the injection parameters as well as some of the vehicle related
outputs such as Fan, AC drivability in gears, variable turbine turbocharger, EGR etc. The ECU receives input
from various sensors located on the engine and the vehicle, and decides the injection quantity, injection timing,
number of injections best suited for the engine to work with maximum efficiency and safety. It is the ‘Brain’ of
the Engine Management System. Being the most important component of the Engine management system,
ECU apart from ensuring the optimum working of the Vehicle, also keeps an eye on the working of the sensors
and actuators. Whenever a malfunction/fault occurs in the component or the system the ECU alerts the user
by glowing MIL indicator on instrument cluster. ECU also does the following:
Stores a DTC in its memory (indicates the faulty component/system).
Stores a context frame (list of parameters indicating the operating condition during the fault generation) in its
memory.
When the malfunction poses a threat to the vehicle, the ECU with its control algorithms operates the vehicle
in Limp Home Mode (safe mode). This protects the component from damage with some degradation in
performance of the vehicle.
• Function: Controls the running of an engine by monitoring the engine speed, load, and temperature. It also
provides the ignition spark at the right time for the prevailing conditions and metering the fuel to the engine in
the precise amount required.

• Components OF Engine management system
1 electronic control unit (ECU),
2 sensors
3 actuators,
4 communication system.

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