POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 0
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 i ENGINE MANAGEMENT SYSTEM TENGKU AZMIE BIN RAJA HASSAN MUHAMAD SHAH RUL BIN KAMARUDDIN POLITEKNIK KOTA BHARU
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 ii ENGINE MANAGEMENT SYSTEM Department of Mechanical Politeknik Kota Bharu KM. 24, Kok Lanas, 16450 Ketereh, Kelantan. ENGINE MANAGEMENT SYSTEM First Printing 2024 © 2024 Tengku Azmie Bin Raja Hassan/Muhamad Shah Rul Bin Kamaruddin All rights reserved. No part of this publication may be reproduced, stored in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the copyright holder. ENGINE MANAGEMENT SYSTEM/ Tengku Azmie Bin Raja Hassan/ Muhamad Shah Rul Bin Kamaruddin
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 iii PREFACE Thanks to Allah SWT for the strength that has been given to us in preparing this topic. We would also like to take the opportunity to express our gratitude to the Head of the Mechanical Engineering Department, En Wan ABD Halim Amir Bin Wan Mohammad for the trust given in carrying out this task. Thanks to Pn Ruzila Binti Mat Ghani, JKM's E-Learning Coordinator, who jointly made revisions and edits, as well as comrades-in-arms who contributed their thoughts and time directly and indirectly in strengthening the content of this book. Thanks to our family who have given us a lot of support. Tengku Azmie Bin Raja Hassan/Muhamad Shah Rul Bin Kamaruddin Department of Mechanical Politeknik Kota Bharu KM 24 Kok Lanas 16450 Ketereh, Kelantan
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 iv SYNOPSIS Engine controls were originally implemented using mechanical devices such as the spark plug, fuel injector, fuel pump and idle air control valve. Although these devices provided acceptable performance in many applications and were relatively inexpensive, they could not provide the level of control needed to meet the emission regulations of today. Many of the control functions performed by these devices are now done electronically using sensors and actuators. The sensors provide information about the operating condition of the engine while the actuators are used to regulate its operation. The ECU processes information from the sensors and determines the desired position for each actuator.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 v AUTHORS BIODATA Tengku Azmie bin Raja Hassan The author was born on 11 December 1977 in Kota Bharu, Kelantan. Has academic qualification in First Degree of Mechanical Engineering and a Master's in Technical and Vocational Education at Tun Hussien Onn University College. Started the career as a lecture at Sultan Azlan Shah Polytechnic, Behrang, Perak in 2005 and Kota Bharu Polytechnic, Kelantan in 2011 until now. Muhamad Shah Rul bin Kamaruddin The author was born on 1986 in Pasir Mas, Kelantan. Has academic qualification in First Degree of Mechanical Engineering (Automotive) (UTeM 2009). Started the career as a lecturer at kota Bharu Polytechnic (PKB) in 2010 until now.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 vi CONTENTS ENGINE MANAGEMENT SYSTEM PREFACE...................................................................................................................... iii SYNOPSIS..................................................................................................................... iv AUTHORS BIODATA ..................................................................................................... v 1.0 ENGINE MANAGEMENT SYSTEM ..................................................................... 1 1.1 Development Of Engine Control System .................................................... 2 1.2 Multipoint Fuel Injection............................................................................... 3 1.3 Single Point Injection ................................................................................... 4 1.4 Direct Injection.............................................................................................. 4 2.0 SUB SYSTEM OF ENGINE MANAGEMENT SYSTEM...................................... 6 2.1 Air Induction System.................................................................................... 6 2.2 Fuel Management System............................................................................ 7 2.3 Control System/Sensor System................................................................... 8 3.0 SENSORS.......................................................................................................... 9 3.1 Exhaust gas (oxygen , Lambda) sensor. .................................................... 9 3.2 Intake Air temperature sensor (IAT).......................................................... 10 3.3 Engine temperature sensor ....................................................................... 11 3.4 Manifold pressure sensor ( MAP sensor ) ............................................... 11 3.5 Throttle position sensor (TPS).................................................................. 12 3.6 Engine temperature sensor ....................................................................... 12 3.7 Air flow sensor OR Mass Air Flow (MAF) Sensor .................................... 13 3.7.1 Hot-Wire Air Flow Meter.......................................................................... 14
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 vii 3.8 Inlet air temperature sensor....................................................................... 14 3.9 Crankshaft position sensor........................................................................ 14 3.10 Knock sensor........................................................................................... 15 3.11 Engine speed sensor............................................................................... 15 3.12 Engine oil sensor..................................................................................... 16 4.0 ACTUATORS ...................................................................................................... 17 4.1 Fuel Pressure Regulator ............................................................................ 17 4.2 Injector......................................................................................................... 17 4.3 Cold start injector....................................................................................... 18 4.4 Fuel Pump ................................................................................................... 19 4.5 Fuel Filter..................................................................................................... 21 4.6 Fuel Tank ..................................................................................................... 21 4.7 Pressure Regulator Pulsation Damper ..................................................... 21 4.8 Spark plug ................................................................................................... 22 4.9 Idle air control valve (IAC valve)................................................................ 22 4.10 Radiator fan.............................................................................................. 23 REFERENCES.............................................................................................................. 24
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 1 1.0 ENGINE MANAGEMENT SYSTEM The Engine Management System (EMS)is responsible for controlling the amount of fuel being injected and for adjusting the ignition timing. Optimum functioning of the EMS assures maximum engine power, with the lowest amount of exhaust emissions and the lowest fuel consumption. Figure 1: Engine Managemet System The EMS is comprised of sensors for intake air and coolant temperature, intake manifold absolute pressure (MAP) and throttle position (TPS), as well as sensors for engine speed and signals for the required injection and ignition spark events, and a sensor for information about the oxygen content in the exhaust. Furthermore, there is an idle speed motor for adjusting and stabilizing the idle speed, or an electronic throttle body and finally a fuel pressure regulator and fuel injector(s). The supplied high-energy ignition coils are controlled by the integrated ignition module. For alternative fuel applications fuel rail pressure and temperature sensors are also utilized.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 2 1.1 DEVELOPMENT OF ENGINE CONTROL SYSTEM The requirements for safety, convenience, economy, and environmental protection have increased continuously, which required an improvement of the related technology. Looking at the engine control system in the beginning the control was made by mechanical means, such as the carburetor and the mechanical distributor. With these systems it was very difficult to acquire optimal engine efficiency while simultaneously satisfying emission control regulations. The next development stages were mechanical fuel injection systems such as socalled K-Jetronic from Bosch, followed by the first electronically controlled systems such as the L Jetronic also from Bosch. Some systems applied only one centralized injector, but usually the latest EMS system uses independent injectors, which can be controlled individually. The systems maintain the optimum conditions for fuel and air intake rate as well as ignition timing to provide the required torque and power and keep the emissions low at the same time. The EMS systems nowadays consist of various sensors detecting the operating conditions of the engine, actuators which are used to influence the operating conditions accordingly, both processed by an electronic device, the control unit. The control unit is processing the data acquired by the sensors to determine the best operating conditions and then drives the actuators accordingly. Let’s start with the basic engine operation to understand the control requirements precisely. Furthermore, it is possible to customize the modern-day ECUs to suit different vehicular applications and varying customer demands. In addition, some cars have an individual ‘Control Module’ for all major systems. A modern car has following individual Control Modules which control the respective systems. i. Electronic/engine control module (ECM) ii. Powertrain control module (PCM) iii. Transmission control module (TCM) iv. Brake control module (BCM) v. Central control module (CCM) vi. Central timing module (CTM) vii. General electronic module (GEM) viii. Body control module (BCM) ix. Airbag control unit (ACU) x. Convenience control unit (CCU) xi. Door control unit (DCU)
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 3 xii. Electric power steering control unit (PSCU) xiii. Telephone control unit (TCU) 1.2 MULTIPOINT FUEL INJECTION Multipoint fuel injection forms the ideal basis for complying with the mixture formation criteria described above. In this type of system each cylinder has its own injector discharging fuel into the area directly in front of the intake valve. Representative examples are the various versions of the KE and L-Jetronic systems. Mechanical injection systems the K-Jetronic system operates by injecting continually, without an external drive being necessary. Instead of being determined by the injection valve, fuel mass is regulated by the fuel distributor. Combined mechanicalelectronic fuel injection Although the K -Jetronic layout served as the mechanical basis for the KE-Jetronic system, the latter employs expanded data-monitoring functions for more precise adaptation of injected fuel quantity to specific engine operating conditions. Electronic injection systems Injection systems featuring electronic control rely on solenoid-operated injection. Figure 2 : Multipoint Fuel Injection
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 4 1.3 SINGLE POINT INJECTION Single-point (throttle-body injection- TBI) fuel injection is the concept behind this electronically controlled injection system in which a centrally located solenoid operated injection valve mounted upstream from the throttle valve sprays fuel intermittently into the manifold. Mono-Jetronic and Mono Motronic are the Bosch systems in this category. Figure 3: Single Fuel Injection 1.4 DIRECT INJECTION Direct-injection (DI) systems rely on solenoid-operated injection valves to spray fuel directly into the combustion chamber; the actual mixture-formation process takes place within the cylinders, each of which has its own injector. Perfect atomization of the fuel emerging from the injectors is vital for efficient combustion.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 5 Figure 4: Direct Injection
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 6 2.0 SUB SYSTEM OF ENGINE MANAGEMENT SYSTEM The three sub systems of engine management system are Air Induction System, Fuel Management System and Control System/Sensor System. 2.1 Air Induction System Figure 5: Air Induction System The air induction system typically consists of an air filter, throttle valve, sensors, and conducting ducts normally known as the throttle body. The throttle valve regulates how much air flows into the engine. In turn, it controls engine power output. Like a carburetor throttle valve, it is connected to the driver’s gas pedal. When the pedal is depressed, the throttle valve swings open to allow more air to rush into the engine.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 7 2.2 FUEL MANAGEMENT SYSTEM Figure 6: Fuel Management System As we now have an overview of the requirements of precise engine control, let’s have a look at the systems applied in Hyundai vehicles. Let’s start with the first sub system, the fuel delivery system which consists of the fuel tank, fuel pump, fuel filter, fuel delivery pipe, fuel injector, fuel pressure regulator and fuel return pipe. Fuel is delivered from the tank to the injector by the electric fuel pump which is typically located in or near the fuel tank. Contaminants are filtered out by a high-capacity fuel filter. In most systems so far, the fuel pressure is kept constant in relation to the manifold pressure by the pressure regulator, to keep the injection amount at the correct level based on the injector opening time. Excessive fuel is returned to the tank. But recently return-less systems are also available. Both types will be described in detail later. Additional parts such as the charcoal canister are installed to reduce the emission of vaporized fuel escaping into the air. Also, this system will be described in detail in the course.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 8 2.3 CONTROL SYSTEM/SENSOR SYSTEM Figure 7: Control System All these controls must be made by the ECU. To make this possible, the engine operating condition is detected by special devices, the so-called sensors. They detect for example the engine speed, the throttle opening and many others. Details about the sensors will follow in section 2 of the engine management system. The ECU is processing the input information from the sensors and controls the output commands accordingly. The output devices are called actuators. The most important actuators are the injectors and the ignition coils, but there are many more actuators in the system. As for the input signals a detailed description of them will follow later. The signal processing and output functions can be divided into six areas: Fuel Injection Control, Ignition Control, Idle Speed Control, Engine and Emission Control, Failure Management (fail-safe and back-up) Self Diagnosis. The ECM employs stored functions and programs to process the input signals transferred by the sensors. These signals serve as a basis for calculating the control signals to the actuators (e.g. ignition coils, injectors).
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 9 3.0 SENSORS The EFI sensor system monitors engine operating conditions and reports or sends this information to the computer (CPU). A typical EFI sensor system consists of an oxygen (Lambda) sensor, engine coolant temperature sensor, air inlet temperature sensor, throttle position sensor, intake manifold pressure (vacuum) sensor, engine speed sensor, and other sensors. An engine sensor is an electrical device that changes circuit resistance or voltage with a change in a condition (Temperature, pressure, position of parts, etc). For example, temperature sensor resistance may decrease as temperature increases. The computer can use the increased current flow through the sensor to calculate any needed change in injector valve opening. Figure 8: EFI sensor system 3.1 EXHAUST GAS (OXYGEN, LAMBDA) SENSOR. It measures the oxygen content in the engine exhaust system as a means of checking combustible efficiency. It fits into the exhaust manifold or pipe at a point before the catalytic converter.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 10 The oxygen sensor voltage output changes with any change in the content of the exhaust. For example, an increase in oxygen (lean mixture) might make the sensor output voltage decrease. A decrease in oxygen (Rich mixture) might cause the sensor output voltage to increase. In this way, the sensor supplies data (Different current levels) to the computer. The computer can then alter the opening and closing of the injectors to maintain a correct air fuel ratio for maximum efficiency. Figure 9: Oxygen sensor 3.2 INTAKE AIR TEMPERATURE SENSOR (IAT) Intake Air temperature sensor senses the air temperature on the inlet side of the engine. The voltage signal, produced by the sensor, is passed to the ECU. The ECU evaluates the signal and influences the fuel injection timing and ignition timing.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 11 Figure 10: Intake Air temperature sensor (IAT) 3.3 ENGINE TEMPERATURE SENSOR The Engine Temperature Sensor accurately measures the engine coolant temperature. Thereby, it gives an indication of temperature of the engine. It is mounted so that it is exposed to engine coolant. When the engine is cold, the sensor might provide a high current flow (Low resistance). The computer would then enrich the air fuel mixture for cold engine operation. When the engine warms, the sensor would supply information (High resistance for example) so that the computer could make the mixture leaner. 3.4 MANIFOLD PRESSURE SENSOR (MAP SENSOR) It measures the pressure (Vacuum) inside the engine manifold. Engine manifold pressure is an excellent indicator of engine load. High pressure (Low intake vacuum) indicates a high load, requiring a rich mixture. Low manifold pressure (High intake vacuum) indicates very little load, requiring a leaner mixture. The manifold pressure sensor changes resistance with changes in engine load. This data is used by the computer to alter the fuel mixture.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 12 Figure 11: Manifold pressure sensor (MAP sensor) 3.5 THROTTLE POSITION SENSOR (TPS) A throttle position sensor is a variable resistor connected to the throttle plate shaft. When the throttle swings open for more power or closed for less power, the sensor changes resistance and signals the computer. The computer can then richen or lean the mixture as needed. Figure 12: Throttle position sensor (TPS) 3.6 ENGINE TEMPERATURE SENSOR The Engine Temperature Sensor accurately measures the engine coolant temperature. Thereby, it gives an indication of temperature of the engine. It is mounted so that it is exposed to engine coolant.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 13 When the engine is cold, the sensor might provide a high current flow (Low resistance). The computer would then enrich the air fuel mixture for cold engine operation. When the engine warms, the sensor would supply information (High resistance for example) so that the computer could make the mixture leaner. Figure 12: Engine temperature sensor 3.7 AIR FLOW SENSOR OR MASS AIR FLOW (MAF) SENSOR An airflow sensor is used in many EFI systems to measure the amount of outside air entering the engine. This helps the computer determine how much fuel is needed. It is usually an air flap or door that operates a variable resistor. Increased airflow opens the flap more to change the position of the variable resistor. Information is then sent to the computer indicating air inlet volume. Engine temperature sensor
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 14 Figure 13: Air flow sensor 3.7.1 HOT-WIRE AIR FLOW METER The MAF sensor uses a heated element, such as a "Hot Wire" or "Heated Film", to determine the "mass" of the incoming air. A small passage inside the sensor directs part of the air flow past the heated element. As more air passes the heated element, heat is carried away by the passing air. As a result, more current is required to maintain the constant temperature of the element. The electronic module converts this electrical current flow into an analog output voltage which varies between 0.4 volts at low air flow to 5 volts at maximum air flow. 3.8 INLET AIR TEMPERATURE SENSOR An inlet temperature sensor measures the temperature of the air entering the engine. Cold air is more dense than warm air, requiring a little more fuel. Warm air is NOT as dense as cold air, requiring a little less fuel. The air temperature sensor helps the computer compensate for changes in outside air temperature and maintain an almost perfect air fuel mixture ratio. Figure 14: Inlet air temperature sensor 3.9 CRANKSHAFT POSITION SENSOR A crankshaft position sensor is used to detect engine speed. It allows the computer to change injector opening with changes in engine rpm. Higher engine speeds generally require more fuel.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 15 Figure 15: Crankshaft position sensor 3.10 KNOCK SENSOR It allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor finds pinging. At that point the computer retards the ignition timing just enough for the pinging to stop. A knock sensor makes sure that you're getting as much power and fuel economy as is possible from your engine at any time. Figure 16: Knock sensor. 3.11 ENGINE SPEED SENSOR The speed sensor measures gear or target wheel speed and position. The Engine Control Module can use this information to modify various engine functions such as Air/Fuel Ratio, ignition timing and perform diagnostic tests.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 16 Figure 17: Engine speed sensor 3.12 ENGINE OIL SENSOR An oil pressure sensor is a device used to measure the oil pressure on an engine. Oil pressure sensor is a term that covers at least two different and distinct types of sensors - an oil pressure switch and and oil pressure sender. Figure 18: Engine oil pressure sensor
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 17 4.0 ACTUATORS Actuators work behind the scenes in vehicles to convert energy into a physical action or force. They perform a variety of performance and convenience functions, from controlling the throttle to directing airflow in the climate control system, and operating power seats and liftgates. 4.1 FUEL PRESSURE REGULATOR The fuel pressure regulator regulates the fuel pressure applied to the injector in such a way that it will always be a predetermined pressure 324-343 kPa, pressure in the intake manifold. This prevents changes in the internal pressure of the manifold from affecting the fuel injection amount. Figure 19: Fuel Pressure Regulator 4.2 INJECTOR An injector is a metering valve which can be controlled by the ECM (Engine Control Module). They consist mainly of the injector housing the injector nozzle and the solenoid. The nozzle is opened or closed in response to the solenoid, which is activated and deactivated by the ECM. One terminal of the solenoid coil is supplied with power if the ignition is switched on. This is done either directly or via the MFI main relay.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 18 The second terminal of the coil is grounded via the ECM. When the ECU driver circuit turns on, current flows to ground through the injector solenoid coil. The magnetic field causes the injector to open against spring tension. When the ECU driver circuit turns off, the spring closes the injector valve. There are two common types of driver circuits currently used on Hyundai engines. Both drivers work on the ground control principle, but one uses an external solenoid resistor and a low resistance injector (0,6 -3 Ohm), the other one uses a high resistance injector (12 -17 Ohm) without separate resistor. As an injector needs to fulfill the following criteria: precise fuel flow rate, good linearity, wide active range, good spray characteristics, no leakage, low noise, and durability many different types are available to cope with the different needs of the different engines. A typical sample for this is the different amount of spray holes, the different shapes of the spray patterns. When installing injectors always use new O rings to avoid leakage and make sure that they are installed correctly in the rail and the manifold. Figure 20: Fuel injector 4.3 COLD START INJECTOR It is bolted into the intake manifold with two Allen-key bolts and is sealed with a large rubber O-ring. It only sprays fuel during the first few seconds when the car is starting, and it only does this when the engine is cold. It only injects fuel when the starter motor is turning. Engines need more fuel than usual when they are cold because combustion of the air/fuel mixture is less efficient at lower temperatures.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 19 Figure 21: Cold start injector 4.4 FUEL PUMP Two kinds of fuel pumps in vehicles: mechanical and electrical fuel pumps. The fuel pump passes the correct amount of fuel from the fuel tank to the carburetor under low pressure or to the fuel injection system under high pressure. The fuel pump control differs slightly, depending on the actual control system manufacturer, but in general the fuel pump is switched on by a signal of the control unit. This signal is given after receiving the CKP signal by the ECU. To facilitate testing and allow pump operation independent of the ECU control, a fuel pump test connector is used, where it is possible to supply current directly to the fuel pump. Another method of forced pump activation is the actuation test (HI-SCAN PRO). Some models are equipped with the auto fuel cut system. This is a safety device to prevent fire when the vehicle crashes, it cuts the power to the fuel pump if the sensor detects the crash. If the vehicle is crashed, a steel ball is moved up, pushes the “moving contact” so that the switch is turned off.
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 20 Above a frontal crash speed of 15miles/hour the fuel pump is surely switched off, below a speed of 8 miles/hour it is not switched off. The range from 9 to 14 miles per /hour is a grey zone, where on or off is possible, depending on exact crash conditions and manufacturing tolerances. The sensor location is on the left-hand side strut housing in the engine room. Resetting the sensor by pushing down the button is required to start the engine after a crash. Figure 22: Internal fuel pump 4.5 FUEL FILTER The main function of a Fuel Filter is to filter out, or trap, debris particles and/or contaminants from flowing fuel. Figure 23: Fuel filter
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 21 4.6 FUEL TANK The fuel tank is a safe container for flammable liquids. often used for gasoline or diesel fuel. storage tank for fuel is used for the part of the engine system where fuel is stored and moved (fuel pump) or released (pressurized gas) into the engineo store the fuel. Figure 24: Fuel tank 4.7 PRESSURE REGULATOR PULSATION DAMPER To regulate fuel pressure in delivery pipe of MPFI engine. Pressure regulator can be used to reduce pulsations in circulating liquid systems, as with positive displacement pumps. Figure 24: Pressure Regulator Pulsation Damper
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 22 4.8 SPARK PLUG The function of the spark plug is to introduce the ignition energy into the engine’s combustion chamber and to initiate combustion of the compressed air-fuel mixture. Figure 25: Spark plug 4.9 IDLE AIR CONTROL VALVE (IAC VALVE) The idle air control valve (IAC valve) is used to control engine idle speed and dashpot functions. The idle air control valve is mounted on the throttle body and allows air to bypass the throttle plate. The amount of air allowed to bypass the throttle plate will be determined by the powertrain control module (PCM) and will be controlled by a duty cycle signal. Figure 26: Idle air control valve (IAC valve)
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 23 4.10 RADIATOR FAN The radiator fan has an important job in the engine compartment. It can push air through the radiator core or pull it through. It must cool the antifreeze that circulates through the block and head passages and reduces the engine temperature. Figure 27: Radiator fan
POLITEKNIK KOTA BHARU MECHNICAL DEPARTMENT DJA30023/TOPIC 1 24 REFERENCES Erjavec J. and Thompson R. (2019), Automotive Technology: A System Approach, 7th Edition, Cengage Delmar Learning. Barton D. C. and Fieldhouse J. D. (2018), Automotive Chassis Engineering, 1st Edition, Springer. Duffy J. E. (2017), Modern Automotive Technology, 9th Edition, The GoodheartWillcox Publisher. Halderman J. D. (2017), Automotive Engines: Theory and Servicing, 9th Edition, Pearson Education. Halderman J. D. (2019), Automotive Technology: Principles, Diagnosis, and Service, 6th Edition, Pearson Education.