unit 4 Engine Electronic Control 《汽车实用英语》.ppt

汽车实用英语,Upon completion of this unit, you should be able to:,Overall Objectives, Learn key terms about engine electronic control systems in this unit. Understand the process of inspection and repair of engine electronic control systems. Use maintenance manual to deal with the practical problems.,Task 4.1 Engine Control System Inspection-发动机控制系统检测 Task 4.2 Fuel Injector Replacement-更换喷油器 Task 4.3 Emission Control Inspection-排放控制检测 Task 4.4 Ignition System Inspection-点火系统检测 Task 4.5 Diagnostic Procedures-诊断程序,Tasks Introduction,Automotive engine control systems must satisfy diverse and often conflicting requirements. Servicing these systems regularly ensures the automotive running normally and meeting stringent standards. The following tasks (e.g. engine control system inspection, fuel injector replacement, ignition system inspection, etc.) are the important items in engine electronic system servicing to control exhaust emissions, fuel economy and other performance indicators of the engine.,Task Description,Task 4.1 Engine Control System Inspection,Learning Preparation,engine electronic system intake air flow meter ohmmeter resistance terminal voltmeter positive negative throttle position sensor knock sensor,Key terms:,发动机电控系统 进气空气流量计 欧姆表 电阻 终端，端子 伏特计，电压表 正极 负极 节气门位置传感器 爆震传感器,Step 1 A maintenance case is provided; Step 2 Learn the process of inspecting the engine electronic system; Step 3 Require students to grasp the key terms in this task; Step 4 Try to describe the process of inspecting the engine electronic system; Step 5 Students read relative material; Step 6 Assessment,Plan and Implement,( ) 1. The resistance of the intake air flow meter is related to the temperature. ( ) 2. When inspecting the voltage of terminal VG and E2G, you should turn off the ignition switch. ( ) 3. If air is blown into the intake air flow meter, the voltage should change with the air flow. ( ) 4. If the resistance of the camshaft timing oil control valve is 7.3 , it is ok. ( ) 5. When testing the movement of the camshaft timing oil control valve, terminal 2 should be connected with the positive lead of the battery.,Assessment and Feedback,True or False,( ) 6. The bad returning the valve may be caused by entrance of foreign objects. ( ) 7. There is a clearance between the throttle stop screw and throttle lever at the throttle closed position. ( ) 8. In the inspection of the throttle position sensor, the resistance between terminals VTA and E2 should change in proportion to the throttle lever opening value. ( ) 9. The water temperature sensor can not be checked in the water. ( ) 10. If the resistance of the knock control sensor is 50k at 20C, it should be changed.,An Air Flow Sensor（空气流量传感器） or Mass Air flow Sensor (MAF) is one of the components of an electronic fuel injection system of a modern car or truck. A mass air flow sensor is installed inside the intake air duct between the air cleaner and the intake manifold of the engine. A mass air flow sensor measures the amount of air entering the engine. Often an intake air temperature sensor (IAT) is also installed within the mass air flow sensor. There are few types of air flow sensors, however a hot-wire type is used the most in the modern cars. Lets see how it works. A hot-wire mass air flow sensor（热线式空气流量计） has a small electrically heated wire (hot wire) and a small temperature sensor installed close to the hot wire. The temperature sensor measures the temperature of the air near the hot wire.,4.1.1 What is a Mass Air Flow Sensor (MAF),Fig4.1.1 Mass Airflow Sensor (MAF) Fig. 4.1.2 Location of the MAF,Fig4.1.3 Toyota mass airflow sensor (MAF) Fig4.1.4Volkswagen mass airflow sensor,When the engine is idling, a very little air flows pass the hot wire, so it takes very small electrical current to keep the wire hot. When you press the gas, the throttle opens allowing more air to flow over the hot wire. The passing air cools the hot wire down; the more air flows over the wire, the more electrical current（电流） is needed to keep it hot. The amount of this electrical current is proportional to the amount of the air flow.,Problems of mass air flow sensors are very common. The air flow sensor usually gets contaminated or damaged when a bad or improperly installed air filter allows some unfiltered（未经过滤的） air into the engine or when oil from an oil-soaked air filter contaminates the air flow sensor. A bad or contaminated mass air flow sensor cannot measure the amount of air flow correctly. This can cause various driveability problems such as stalling, especially when the engine is cold, misfiring, lack of power, poor acceleration, etc. In addition, a problem with the mass air flow sensor will cause the Check engine or Service engine light to come on.,4.1.2 Mass Air Flow Sensor Problems,The “check engine” light comes on when the computer has detected a fault in one of the engine electronic systems. This fault（故障） is stored as a trouble code and can be retrieved from the computer with a scan tool. The following trouble codes are associated with a mass airflow sensor: P0100 - Mass Air Flow Circuit Malfunction P0101 - Mass Air Flow Circuit Range/Performance P0102 - Mass Air Flow Circuit Low P0103 - Mass Air Flow Circuit High P0104 - Mass Air Flow Circuit Intermittent The trouble codes P0171 System Too Lean (Bank 1) and P0174 System Too Lean (Bank 2) are also could be caused by a bad or contaminated mass air flow sensor. If your check engine light is on, have your vehicles computer scanned and read more about lean codes.,Often, an air flow sensor can be checked with a scan tool. Usually, the air flow readings of the sensor in question is compared to the readings of a known good sensor. Typically, a contaminated air flow sensor will show different amount from a known good sensor. If the air flow sensor is bad, it will need to be replaced. Its a fairly simple job, however the air flow sensor itself could cost up to a few hundred dollars. If the sensor is just dirty, your mechanic may suggest cleaning it (cleaning the airflow sensor is a delicate procedure) as a temporary solution sometimes this could help you. If the new mass air flow sensor is installed, make sure the air filter is installed properly, as the sand particles coming with the unfiltered air can damage the air flow sensor.,Practice Maintenance Manual Reading,1. Intake air flow meter SUB-ASSY. (a) Inspect the intake air flow meter resistance. (1) Using an ohmmeter, measure（测量） the resistance between terminals THA and E2.,Engine Control System Inspection,HINT: If the resistance is not as specified, replace the intake air flow meter. (b) Inspect the intake air flow meter operation. (1) Connect the intake air flow meter connector. (2) Turn the ignition switch（点火开关） to ON. (3) Using a voltmeter, connect the positive (+) tester probe to terminal VG, and negative () tester probe to terminal E2G. (4) Blow air into the intake air flow meter, and check that the voltage fluctuates.,HINT: If operation is not as specified, replace the intake air flow meter. (5) Turn the ignition switch to LOCK. (6) Disconnect the intake air flow meter connector.,2. Camshaft timing oil control valve ASSY (a) Resistance inspection. (1) Using an ohmmeter, measure the resistance between the terminals. Resistance: 6.9 to 7.9 at 20C (68F) (b) Movement inspection. (1) Connect the positive (+) lead from the battery（蓄电池） to terminal 1 and negative () lead to terminal 2, and check the movement of the valve.,NOTICE: Confirm the valve does not adhere. HINT: Bad returning of the valve（阀） by entrance of foreign objects causes subtle pressure leak to the advanced direction. Then, DTC can be detected.,3. Throttle body ASSY Check throttle body. (1) Check that throttle valve shaft is not rickety. (2) Check that each port is not stopped up（堵塞）. (3) Check that throttle valve opens and closes smoothly. (4) Check that there is no clearance between the throttle stop screw and throttle lever at the throttle closed position.,NOTICE: Do not adjust the throttle stop screw.,4. E.F.I. Throttle Position Sensor (a) Resistance inspection. (1) Disconnect the throttle position sensor connector. (2) Using an ohmmeter, measure the resistance between terminals VC and E2. Resistance: 2.5 to 6.0 k (3) Check the change of resistance between terminals VTA and E2. Change of resistance: The resistance value（电阻值） increases in proportion to the throttle lever opening value.,5. E.F.I. Engine Coolant Temperature Sensor (a) Resistance inspection. (1) Using an ohmmeter, measure the resistance between each terminal. Resistance: At 20C (68F) 2.32 2.59 k At 80C (176F) 0.310 0.326 k NOTICE: In case of checking the water temperature sensor（水温传感器） in the water, be careful not to allow water to go into the terminals, and after checking, wipe out the sensor.,6. Knock Control Sensor (a) Using an ohmmeter, measure the resistance between terminals. Resistance: 120 280 k at 20C (68F) HINT: If the resistance is not specified, replace the sensor.,HINT: If the resistance is not specified, replace the sensor.,7. E.F.I. Circuit Opening Relay（继电器） ASSY (a) Continuity inspection. (1) Using an ohmmeter, check that continuity exists between each terminal. Specified condition: Between terminals 1 and 2 Continuity Between terminals 3 and 5 No continuity (2) Using an ohmmeter, check that continuity exists between terminals 3 and 5 when he battery voltage is applied across terminals 1 and 2.,Task 4.2 Fuel Injector Replacement,Learning Preparation,fuel injector cylinder head cover ventilation hose retainer connector insert fuel delivery pipe twist,Key terms:,喷油器 汽缸盖罩 通风软管 保持架 接头，连接器 插入 燃油分配管 扭转，扭曲,Step 1 A maintenance case is provided; Step 2 Learn the process of replacing fuel injector via a maintenance manual; Step 3 Require students to grasp the key terms in this task; Step 4 Try to describe the process of replacing fuel injector; Step 5 Students read relative material; Step 6 Assessment,Plan and Implement,( ) 1. When you replacing the injectors, you must prevent the gasoline leakage. ( ) 2. The ventilation hose is connected with the cylinder block. ( ) 3. The engine is a type of multi-point fuel injection. ( ) 4. The harness clamps are used to fix the wires. ( ) 5. An SST must be adopted to disconnect the fuel tube.,Assessment and Feedback,True or False,( ) 6. The pipe and the connector should be kept very clean. ( ) 7. The fuel injectors should be removed with the fuel delivery pipe. ( ) 8. The insulator installed on each fuel injector needs not to be changed. ( ) 9. When installing the injector to the fuel delivery, you can apply a little engine oil on the O-ring. ( ) 10. The injector should be pushed directly to the fuel delivery pipe.,The EFI (Electronic Fuel Injection) system（电控燃油喷射系统） uses sensors to detect the engine condition and vehicle running condition. And the engine ECU（电控单元） calculates the optimum fuel injection volume, and causes the injectors to inject the fuel. Fig. 4.2.1 shows the basic EFI configuration.,4.2.1 Electronic Fuel Injection System,Fig. 4.2.1 Electronic Fuel Injection System 1- exhaust gas oxygen sensor; 2-injector; 3- fuel pressure regulator; 4-coolant temperature sensor; 5-idle control valve; 6-air flow meter; 7- fuel tank; 8- fuel pump; 9- fuel filter; 10-ECU,The Electronic Fuel Injection system can be divided into three basic subsystems: the fuel delivery system, the air induction system and the electronic control system. The fuel delivery system consists of the fuel tank（油箱）, fuel pump, fuel filter, fuel delivery pipe (fuel rail), fuel injector, fuel pressure regulator, and fuel return pipe. Some engines also have pulsation damper. The fuel is taken from the fuel tank by the fuel pump and sprayed under pressure by an injector. The fuel pressure in the fuel line must be regulated to maintain stable fuel injection by the pressure regulator. Any fuel which is not delivered to the intake manifold by the injector（喷油器） is returned to the tank through a fuel return pipe.,The air induction（空气供给） system consists of the air cleaner, air flow meter, throttle valve, air intake chamber, intake manifold runner, and intake valve. When the throttle valve is opened, air flows through the air cleaner, through the air flow meter, past the throttle valve, and through a well tuned intake manifold runner to the intake valve. Air delivered to the engine is a function of driver demand. As the throttle valve is opened further, more air is allowed to enter the engine cylinder. The electronic control system consists of various engine sensors, Electronic Control Unit (ECU), various actuators. There are many sensors such as mass airflow sensor, manifold absolute pressure sensor, throttle position sensor, engine coolant temperature sensor, intake air temperature sensor, crankshaft position sensor, camshaft position sensor, and exhaust gas oxygen sensor, etc.,The basic function of the ECU is to control the pulse width of the injector. In engine management systems, the ECU controls additional functions, such as idle speed（怠速）, ignition timing, and fuel pump operation. The actuators（执行元件） contain fuel pump relay, injector, Malfunction Indicator Light (MIL), EVAP canister purge solenoid valve, air conditioner relay, cooling fan relays, idle control valve, etc. Air enters the engine through the air induction system where it is measured by the air flow meter. As the air flows into the cylinder, fuel is mixed into the air by the fuel injector. Fuel injectors are arranged in the intake manifold behind each intake valve. The injectors are electrical solenoids which are operated by the ECU. The ECU pulses the injector by switching the injector ground circuit on and off.,When the injector is turned on, it opens, spraying atomized fuel at the back side of the intake valve. As fuel is sprayed into the intake airstreams, it mixes with the incoming air and vaporizes due to the low pressure in the intake manifold. The ECU signals the injector to deliver just enough fuel to achieve an ideal air/fuel ratio（空燃比） of 14.7:1, often referred to as stoichiometry. The precise amount of fuel delivered to the engine is a function of ECU control. The ECU determines the basic injection quantity based upon measured intake air volume and engine rpm（转速）. Depending on engine operating conditions, injection quantity will vary. The ECU monitors variables such as coolant temperature, engine speed, throttle angle and exhaust oxygen content and makes injection corrections which determine final injection quantity.,A fuel injector is nothing but an electronically controlled valve. It is supplied with pressurized fuel by the fuel pump in your car, and it is capable of opening and closing many times per second. When the injector is energized, an electromagnet moves a plunger that opens the valve, allowing the pressurized fuel to squirt out through a tiny nozzle（喷嘴）. The nozzle is designed to atomize the fuel to make as fine a mist as possible so that it can burn easily.,4.2.2 Injector,Fig. 4.2.2 Inside a Fuel Injector,Fig. 4.2.3 Location of the Fuel Injectors,The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open. This is called the pulse width, and it is controlled by the ECU. The injectors are mounted in the intake manifold so that they spray fuel directly at the intake valves. A pipe called the fuel rail supplies pressurized fuel to all of the injectors.,Practice Maintenance Manual Reading,1. Work for Preventing Gasoline from Spilling Out 2. Remove Cylinder Head Cover NO.2 (a) Remove the 2 nuts（螺母）, 2 clips and cylinder head cover.,Fuel Injector Replacement,3. Disconnect Ventilation Hose (a) Disconnect the ventilation hose from the cylinder head cover.,4. Disconnect Engine Wire (a) Disconnect the 4 fuel injector connectors. (b) Remove the 3 wire harness clamps from the clamp brackets.,5. Remove EFI Fuel Pipe Clamp (a) Remove the EFI fuel pipe clamp.,6. Disconnect Fuel Tube SUB-ASSY (a) Using an SST, disconnect the fuel tube. (SST=Special Service Tool) SST 0926821010 (1) Assemble the SST to the connection as shown. (2) Turn the SST, align the retainers inside the connector with the SST chamfered parts and insert the SST into the connector. (3) Slide the SST and the connector together towards the fuel tube assembly,7. Remove Fuel Delivery Pipe SUBASSY Remove the 3 bolts and fuel delivery pipe（燃油分配管） together with the 4 fuel injectors. NOTICE: Be careful not to drop the fuel injectors when removing the fuel delivery pipe.,8. Remove Fuel Injector ASSY (a) Pull out the 4 fuel injectors from the fuel delivery pipe.,9. Install Fuel Injector ASSY (a) Install a new insulator to each fuel injector. (b) Apply a light coat of spindle oil or gasoline to a new O-ring, and install it to each fuel injector. NOTICE: Never use engine, gear or brake oil.,(c) Apply a light coat of spindle oil or gasoline on the place where the fuel delivery pipe touches on the O-ring. (d) While turning the fuel injector clockwise and counterclockwise, push it to the fuel delivery pipe. NOTICE: Be careful not to twist the O-ring. After installing the fuel injectors, check that they turn smoothly. If the fuel injector does not, reinstall it with a new O-ring.,10. Install Fuel Delivery Pipe SUBASSY (a) Install the 2 spacers to the cylinder head. (b) Install the fuel delivery pipe together with the 4 fuel injectors with the 3 bolts. Torque: Bolt A 19 Nm (194 kgfcm, 14 ftlbf) Bolt B 9.0 Nm (92 kgfcm, 80 in. lbf) NOTICE: Be careful not to drop the fuel injectors when installing the fuel delivery pipe. Check that the fuel injectors rotate smoothly after installing the fuel delivery pipe.,11. Connect Fuel Tube SUBASSY (a) Connect the fuel tube to the fuel delivery pipe. NOTICE: Check if there is any damage or foreign objects on the connected part of the fuel tube. After connecting, check if