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1.5L REVOTORQ ENGINE
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9. ENGINE MANAGEMENT SYSTEM
A. ABBREVIATIONS
CAN
Control Area Network
GND
Ground
V batt
Battery
IPC
Instrument Panel Cluster
IGN
Ignition
DTC
Diagnostic Troubleshooting Code
OBD
On Board Diagnostic
HVAC
Heating Ventilation Air Conditioning
ECU
Electronic Control Unit
TML
Tata Motors Ltd.
HU
Head Unit
TCM
Transmission Control Module
ECM
Engine Control Module
MTO
Message Time Out
CRC
Cyclic Redundancy Check
MRC
Message Rolling Counter
B. AN OVERVIEW
Engine Management System Overview
Modern engine management systems do a fine
job of ensuring that engines run cleanly and
efficiently in a wide variety of conditions, they are
for the most part reliable and require little or no
maintenance.
Engine management system Comprises of
Electronic Control Unit (ECU), Sensors, Actuators,
Wiring Harness and control algorithms, which
determine the performance of the Engine as a
whole and as part of the vehicle.
Electronic Control Unit (ECU)
The Electronic control Unit is a 32 bit
microprocessor which controls the injection
parameters as well as some of the vehicle related
outputs such as Fan, AC drivability in gears, 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.
Input to the ECU is received from Crank sensor,
Cam sensor, Vehicle speed sensor, Pedal sensor,
Rail Pressure Sensor, Fuel Temperature sensor,
Coolant temperature sensor, Air mass flow
sensor, Boost Pressure and atmospheric pressure
sensor, water-in-fuel sensor, pump mounted
sensor.
Based on all these inputs, the ECU controls all the
injectors directly. It also controls the Inlet metering
valve on the High pressure pump, Engine cooling
Fans, Air conditioning and Exhaust Gas
Recirculation (EGR) valve.
The injection parameters are corrected for various
atmospheric conditions like cold and hot climates
and different Altitudes. Corrections are also
applied considering engine safety in case of faults
and any abnormal overheating. Fault detection is
made simple. Faults are recorded in the ECU
which makes it easy to be read with the help of a
diagnostic tool and to find a solution.
Sensors:
A sensor is a device that measures a physical
quantity and converts it into an electrical voltage
which can be read by an instrument or used by
some controller for its purpose.
Actuators
An actuator causes an action (say injector open or
close) based on command given by ECU.
Wiring Harness
Engine Wiring Harness and Vehicle Wiring
Harness interface the Engine and Vehicle
components to Engine Control Unit.