2. • The Electronic Fuel Injection system can be
divided into three: basic sub-systems. These
are the fuel delivery system, air induction
system, and the electronic control system
3. The basic functions installed in an ECU of
ECES is:
1.Fuel injection control (EFI) function
2.Ignition control function
3.Idle speed control function (ISC/AAC)
4.Diagnosis function
5.Fail safe function
6.Back up function
4. 1. Fuel injection control
• Signal from different sensors are received to
determine two things.
a). Injection timing
b). Injection duration
5. Cont..
• Injection timing control – determines when injectors
will inject fuel in to the port
• Injection duration control – determine how much fuel
will be injected.
Can be determined by
basic injection signals (engine RPM & intake air
volume signals)
correction injection signals (battery, engine temp, etc.)
7. Ignition control function
• Ensures optimal ignition timing based on data
provided from sensor that monitor various
engine operating conditions
Example
crank angle sensor (G –signal)
engine speed sensor (NE – signal)
manifold pressure sensor (PIM – signal)
coolant temperature sensor (THW – signal)
Etc.
9. Idle speed control
ECU is programmed with target engine speed
values to respond to different engine
conditions such as:
Coolant temperature
air conditioner on/off
(A/C)
10. DIAGNOSTIC FUNCTION
• If the ECU detects any malfunctions in the input
data (signal) it stores data on its memory and
displays the malfunction on a tester or by the help
of check engine lamp.
11. Fail-safe function
• If the signals input to the engine ECU is
abnormal, the ECU switches to standard
values stored in its internal memory to control
the engine.
15. Engine
Management
Layout
Sensors Actuators
ECU
The engine control
system includes:
SENSORS for the
detection of the engine
operating modes
ELECTRONIC CONTROL UNIT(ECU) which
elaborates the signal values supplied by the sensor,
according to defined control strategies and algorithms,
and defines the actions to be delivered to the actuators
ACTUATORS which
have the task to actuate
the defined commands
16. Engine Management Layout
Sensors
What is a sensor?
Sensors are transducers that change physical quantity in to
electrical quantity
They are of two types:
Active (self generating)
Knock sensor
O2 sensor(zirkoniya type
Induction type
Passive (modulators)
Throttle Position Sensor
MAF Sensor
17. The key sensors
Air Flow Meter
The air flow meter is used with L-type EFI for sensing the intake air volume.
In L-type EFI, this is one of the most important sensors.
The intake air volume signal is used to calculate the basic injection
duration and basic ignition.
Types of Air Flow Meter
Vane/ FLAP Type (VAF)
Optical Karman Vortex Type
(VAF)
Hot Wire Type (MAF)
The First two measures intake air amount by
volume but hot wire type measures air mass.
18. The key sensors
Air Flow Meter
Vane/ FLAP Type (VAF) for L – Type EFI
Construction
19. The key sensors
Air Flow Meter
Vane/ FLAP Type (VAF) for L – Type EFI
Operation
The principle used here is the measurement of force exerted in the sensor
flap by the air passing through it.
20. Air Flow Sensor Terminal Identification
(First Design Sensor
22. The key sensors
Air Flow Meter
Optical Karman Vortex Type (VAF) for L – Type EFI
This type of air flow meter directly senses the intake air volume optically.
Compared to the vane type, it is made smaller and lighter in weight.
Also reduces inlet resistance of the intake air.
Construction
23. Air Flow Sensor Terminal Identification
(Second Design Sensor)
25. The key sensors
Air Flow Meter
Optical Karman Vortex Type (VAF) for L – Type EFI
Construction
26. The key sensors
Air Flow Meter (Hot Wire Mass Air Flow meters)
Mass flow meters operate according to the hot-wire or hot-film principle without
any moving mechanical part inside the unit.
The closed-loop control circuit in the meter’s housing maintains a constant
temperature differential between a fine platinum wire or thin-film resistor and the
passing air stream.
The current required for heating
provides an extremely precise, albeit
nonlinear, index of air-mass flow rate;
the ECU converts the signal into linear
form.
Due to its closed-loop design, this air-
mass meter can monitor flow
variations in the millisecond range.
27. The key sensors
Hot-wire Air Flow Meter
Operating Principle
If a heated metal wire (hot wire) is exposed to air flow, its temperature drops
as the heat is removed from the wire.
28. The key sensors
Hot-wire Air Flow Meter
Operating Principle
When the temperature of the hot wire is considered to be maintained at a
constant value, a certain relationship occurs between the air flow quantity
and the current flow that maintains the constant temperature of the hot wire.
29. The key sensors
Intake Manifold Pressure Sensor (for D-EFI)
This sensor detects the pressure variation of the intake manifold and converts it to
the voltage signal.
The intake air volume signal is used to calculate the basic injection duration and
basic ignition.
Intake manifold pressure is a directly related to engine load.
The ECM needs to know intake manifold pressure to calculate how much fuel to
inject, when to ignite the cylinder, and other functions.
The MAP sensor is located either directly on the intake manifold or it is mounted
high in the engine compartment and connected to the intake manifold with
vacuum hose.
The MAP sensor uses a perfect vacuum as a reference pressure.
The difference in pressure between the vacuum pressure and intake manifold
pressure changes the voltage signal.
The MAP sensor converts the intake manifold pressure into a voltage signal (PIM).
30. The key sensors
Intake Manifold Pressure Sensor (for D-EFI)
Construction
31. The key sensors
Intake Manifold Pressure Sensor (for D-EFI)
Operation
On the other side is the pressure to be measured. The silicon chip changes its
resistance with the changes in pressure.
When the silicon chip flexes with the change in pressure, the electrical
resistance of the chip changes.
In the Manifold Absolute Pressure
(MAP) sensor there is a silicon
chip mounted inside a reference
chamber.
On one side of the chip is a
reference pressure. This reference
pressure is either a perfect
vacuum or a calibrated pressure,
depending on the application.
This change in resistance alters the voltage signal. The ECM interprets the
voltage signal as pressure and any change in the voltage signal means there was
a change in pressure.
34. The key sensors
Throttle Position Sensor
The throttle position signal is used for fuel cut off
control (during deceleration or braking) and increasing
the fuel volume during acceleration.
The TPS is mounted on the throttle body and converts
the throttle valve angle into an electrical signal. As the
throttle opens, the signal voltage increases.
The ECM uses throttle valve position information to
know:
engine mode: idle, part throttle, wide open
throttle.
switch off AC and emission controls at Wide
Open Throttle (WOT).
air-fuel ratio correction.
power increase correction.
fuel cut control.
36. The key sensors
Throttle Position Sensor
Operation
The basic TPS requires three wires.
Five volts are supplied to the TPS from
the VC terminal of the ECM.
At idle, voltage is approximately 0.6 - 0.9
volts on the signal wire.
From this voltage, the ECM knows the
throttle plate is closed.
37. The key sensors
Throttle Position Sensor
Operation of point type TPS
The basic TPS requires three wires.
Five volts are supplied to the TPS from
the VC terminal of the ECM.
A ground wire from the TPS to the E2
terminal of the ECM completes the
circuit.
At idle, voltage is approximately 0.6 - 0.9
volts on the signal wire.
From this voltage, the ECM knows the
throttle plate is closed.
At wide open throttle, signal voltage is
approximately 3.5 - 4.7 volts.
39. The key sensors
Throttle Position Sensor
Operation linear type
Inside the TPS is a resistor and a wiper
arm.
The arm is always contacting the resistor.
At the point of contact, the available
voltage is the signal voltage and this
indicates throttle valve position.
At idle, the resistance between the VC (or
VCC terminal and VTA terminal is high,
therefore, the available voltage is
approximately 0.6 - 0.9 volts.
As the contact arm moves closer the VC
terminal (the 5 volt power voltage),
resistance decreases and the voltage
signal increases.
41. WATER TEMPERATURE SENSOR
• This sensor detects the engine coolant water
temperature by means of a thermistor.
• Based on the signal from the
sensor, the ECU increases fuel volume to improve drive
ability during cold engine operation.
43. INTAKE AIR TEMPERATURE SENSOR (THA)
• Even though the volume of air measured by the air
flow meter may be the same, the fuel injection
volume will vary with the air temperature.
• The ECU adjusts injection volume slightly, according
to the intake air temperature.
44. LAMDA SENSOR (OXYGEN SENSOR)
• The O2 sensor senses whether the air fuel
ratio is richer or leaner than the theoretical air
fuel ratio.
45. Types of oxygen sensors
• Zirconia element
type
Operation: If the oxygen
concentration on the
inside surface of ZrO2
element differs greatly
from that on the outside
surface at high
temperature (it works
400oC/752oF or higher),
the zirconia element
generates a voltage,
which acts as an OX signal
to the engine ECU.
46. • The ECU comparator circuit is designed to
monitor the voltage from the sensor and send a
digital signal to the microprocessor.
• If sensor voltage is above the comparator switch
point, z 1/2 volt, the comparator output will be
high. If the sensor voltage is below the
comparator switch point, the comparator output
will be low.
• The microcomputer monitors the output of the
comparator to determine how much oxygen
remains in the exhaust stream after combustion
occurs.
47. Oxygen Sensor Heater Circuits (HT)
• Oxygen sensors work very efficiently when the
sensing element temperature is above 750'F (400'C).
• when the engine is first started or when idling or
when driving under very light load, the oxygen sensor
can cool down, forcing the fuel system to return to
open loop operation.
• The oxygen sensor heater control system maintains
sensor accuracy by turning on the heater element
whenever intake air volume is low (exhaust
temperatures are low under these conditions). By
heating the sensor electrically, sensor detection
performance is enhanced
48. • .
The ECU monitors the following parameters and cycles the
oxygen sensor heater on:
• When intake air flow is below a given point.and
• coolant temperature is above approximately 32'F (O'C).
• specified time has elapsed after starting
Whenever the above mentioned conditions are met, the
ECU turns on the driver transistor to supply a ground path
for heater current.
51. Titania element type OPERATION:
• The properties of titania are such that its resistance
changes in accordance with the oxygen concentration of
the exhaust gas. This resistance changes abruptly at the
boundary between a lean and a rich theoretical air-fuel
ratio,
• The ECU comparator circuit is designed to monitor the
voltage drop across R1. As the voltage drop across the
sensor increases, the drop across R1 decreases and vice
versa. This gives the OX signal voltage the same
characteristic as the Zr02 sensor
• A one-volt potential is supplied at all times to the OX+
terminal of the sensor. The resistance value of the sensor
changes abruptly as the stoichiometric boundary is crossed.
53. • If sensor voltage drop is low, as it would be with a rich
mixture, OX signal voltage will be above the comparator
switch point, 450 millivolts, and the comparator output
will be high. If the sensor voltage drop is high, OX signal
voltage will be below the comparator switch point and
the comparator output will be low.
Sub-Oxygen Sensor (OX2)
• The sub-oxygen sensor is used on California and some
Federal engines. It is used to monitor the exhaust
stream after the catalyst to determine if the air/fuel
mixture is within the range for efficient converter
operation
54. • The sub-oxygen sensor is identical to the
Zr02 main oxygen sensor located ahead of
the catalyst. Information from this sensor is
used by the ECU to fine tune the air/fuel ratio
and improve emissions.
56. Knock sensor
• When engine detonation occurs, vibration of the
cylinder block causes the sensor to generate a voltage
signal. The sensor signal varies in amplitude depending
on the intensity of knock.
• The use of knock sensors enables an engine to run on
the threshold of knock’ and should knock occur the
sensor feeds the information back to an electronic
control unit which retards the ignition timing to reduce
the knock detected.
57. • There are two different types of knock sensors used on
Toyota engines.
• The mass type sensor produces a voltage output over a
wide input frequency range; however, its signal output is
greatest at a vibration frequency of approximately 7KHz.
With this type of sensor, the ECU uses a filter circuit to
distinguish between background noise and actual engine
knock.
• The resonance type sensor is tuned into a very narrow
frequency band and only produces a significant signal
voltage when exposed to vibrations in the 7KHz range.
The ECU requires less complicated filter circuitry with
this type of sensor.
58. • When engine detonation occurs, the ECU
monitors knock sensor signal feedback to
determine the degree of detonation taking place.
• This is accomplished by filtering out sensor signal
voltage which does not go above preprogrammed
amplitude parameters. Because other
background noise and vibration cause some
signal output from the knock sensor, the ECU is
also programmed to filter out any signal which
does not fall within certain frequency ranges
60. CRANK ANGLE SENSOR & ENGINE SPEED SENSOR
(TOYOTA)
• These signals are used by the Engine ECU to
detect the crankshaft angle and engine speed.
These signals are very important not only for
the EFI system but also for the ESA system.
We can classify in to three types depending on
their installation position
• In-distributor type
• Cam position sensor type
• Separate type
62. A. NE SIGNAL
The NE signal is used by the Engine ECU to
detect the engine speed
Construction and operation
63. B. G SIGNAL
• The G signal informs the Engine ECU of the
standard crankshaft angle, which is used to
determine the injection timing and ignition timing
in relation to the TDC
65. VEHICLE SPEED SENSOR
• This sensor senses the actual speed at which
the vehicle is traveling.
• Used to control ISC system and air fuel ratio
during acceleration, deceleration, etc.
1. Reed switch type
