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汽车怠速故障(The car broke down)

2018-04-30 10页 doc 37KB 29阅读

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汽车怠速故障(The car broke down)汽车怠速故障(The car broke down) 汽车怠速故障(The car broke down) The basic idea of troubleshooting (1) failure confirmation The control system of the electric control engine (ECU) controls only the electric control part of the engine, not the whole engine, especially the m...
汽车怠速故障(The car broke down)
汽车怠速故障(The car broke down) 汽车怠速故障(The car broke down) The basic idea of troubleshooting (1) failure confirmation The control system of the electric control engine (ECU) controls only the electric control part of the engine, not the whole engine, especially the mechanical part. The ECU of the electric control engine cannot monitor the failure caused by the following reasons. (1) the ECU of a normal low-frequency vehicle cannot monitor the failure of a high-voltage ignition circuit caused by a non-working ignition coil, pollution or damaged spark plugs, and high voltage line broken core. (2) the ECU cannot monitor the flow of the imported filter, fuel filter line, the oil inlet line or the backpipe of the oil filter, the oil is not smooth, or the mixture is too weak. (3) ECU can't monitor the air flow changes caused by air traffic changes due to the failure of air filter or air filter to plug or throttle the flow. (4) the ECU cannot monitor the pressure of the cylinder or the uniformity of the pressure of the cylinder. (5) the ECU can not monitor the plug and pin damage, but it will produce the fault code caused by this condition. (6) the ECU cannot monitor the grounding, but it will produce the fault code caused by this condition. (7) monitoring ECU can't vacuum booster in engine control system of vacuum line leak or throttling, yet the intake manifold absolute pressure sensor vacuum will be monitored and ECU can also record the fault codes. The above 10 is the reason for the failure of the electric control engine to be detected, and should be taken seriously in the maintenance of electric control engine. It is the electrical fault or mechanical fault that must correctly distinguish the location and the characteristic of the performance, so that the fault can be quickly and accurately determined. In the inspection, if the engine fails, and the engine's obstacle warning light is not lit (undisplayed), the engine failure may be in the mechanical part. Generally speaking, mechanical failures occur in the following situations: the spark plug and the high-pressure line itself are defective; The engine crankcase forced ventilation valve or pipe blockage; Congestion of air filter; Defects in the air leakage or vacuum tube near the suction pipe are defective, and the faults caused by these parts are not part of the electrical control part of the fault, but they all cause the engine to malfunction. For example, when the spark plug and the high pressure line have defects, the engine may not stabilize, accelerate the failure of fire, exhaust pipe and so on. For example, if the air flow meter is damaged causing leakage, the ECU monitoring error will result in the engine speed loss and the failure of operation. Above the failure of mechanical parts mostly belong to small and large valve-train mechanical failure occurred in (with gas phase loses, broken valve springs, and blockage of the hydraulic lifter) and right (timing gear mark) on the ignition timing. The gas phase and ignition timing are not correct and should be disassembled. In addition to the above, there are cylinder and piston ring fit clearance is too large, engine oil and bearing ring also belong to the scope of mechanical failure, electronic control system monitoring, fault is easy to determine, this part is not easy to confuse. (2) failure analysis The electromagnetic switches, solenoid valves, relays, motors and fuel injectors of electric control motors will make a certain noise during normal operation. If the noise becomes smaller, the noise is irregular or no noise, the device or the circuit can be judged to be faulty. (3) troubleshooting items before troubleshooting (1) check whether the fuse is damaged. (2) check the air filter and the gasoline filter, check the filter core and whether there are any dirt, impurities and pollutants around it, and clean and replace the filter element if necessary. (3) check whether the vacuum pipes are seepage, clogging and poor connection, and whether the vacuum hose is damaged and aging. (4) check whether the connection of the electrical control system wire is good, whether it is loose, disconnecting and shedding, especially in the connection part. (5) check for any visible damage to each sensor and actuator. (6) check whether the engine is leaking during operation and whether the exhaust manifold and oxygen sensor are leaking. (7) check whether the fuel injector has dirt and fuel injection pressure within the specified range. (8) check whether the high pressure is normal. (9) check whether the cylinder pressure is within the specified range. (10) listening to the engine is the same. On the basis of the above inspection, the basic working principle of the engine and the principle of electric control injection are used to comprehensively analyze the oil circuit, circuit and gas path scientifically. Find out what factors are related to failure. From simplicity to complexity, from easy to difficult, from external to internal, to find out the real reason for the failure, and try to exclude it. Data flow and waveform of difficult fault analysis of electric control engine My space information will be updated every day. I hope the information in it will help you. Let's see more data plus 609688241 Data flow and waveform analysis fault method The analysis of data flow and waveform analysis is the basic method to eliminate the fault of electric control engine. Because this approach requires a certain theoretical basis and some necessary technical data and result in a generally used in the electronically controlled engine failure is less, and are mostly used on exclude the troubleshooting of electronic-controlled engine. (1) troubleshooting with data flow The electric control system of some of the main sensors and actuators work normally when the values of the parameters (such as speed, battery voltage, air flow rate, injection time, the throttle opening, ignition advance Angle, coolant temperature, etc.) provided to WeiXiuZhe, then according to the requirements of different combination, form the data group, it's called data flow. These standard data streams are provided by the factory or are extracted from the normal driving car, which can monitor the working conditions of the engine in various situations. In the case of the electric car, the fault self-diagnosis system has the ability to record the data in the car. Using these data can be in the form of the fault detector, various sensors and actuators of input and output signal instantaneous value displayed on the screen in the form of data, so that we can according to the change of all kinds of data in the working process of the automobile (there is failure data) and the standard of data or data under normal operation flow, can be the cause of the fault diagnosis of electronic control system. For example, A shenyang jinbei vans, after starting engine, warming-up stage work is normal, normal operation for a period of time, temperature, engine with discontinuous phenomenon of smoke, accelerate the exhaust pipe will also send out chug sound, power down, serious when will not shift. Because of the lack of power, the exhaust pipe has a sudden sound, the reason may be: the individual cylinder work is not good, smoke black smoke, explain the mixture gas concentration has the problem. After checking the circuit (spark plug, ignition coil, high voltage line) and oil road, no abnormality was found. The fault reason may be on the intake system. With the diagnosis of the detector, the non-fault code shows that the main data of its idle speed are extracted using the data flow diagnosis method (without fault). The main data is as follows: Engine speed of 760 ~ 800r/min Spray oil pulse 0.6 ms The ignition advance Angle 7 ? ~ 14 ? Inlet pressure 30.8 kPa Coolant temperature 80 ? The throttle opening < 5.5 ? When the road test, after driving several dozens of kilometers, the engine appeared the above fault phenomenon. A step on the accelerator pedal, the exhaust pipe has a dull thudding sound, and then the data flow of the idle condition is observed. The main data is as follows: Engine speed: 560 ~ 920r/min Spray oil pulse 4.5 ms The ignition advance Angle 7 ? ~ 21 ? Inlet pressure 100.2kpa Coolant temperature 92 ? The throttle opening < 5.5 ? The most obvious change in the comparison between the data flow of the engine and the data flow of the cold machine is the two data of the intake pressure and the oil injection pulse. From the above data, the reason of the fault may be in the intake system, which may be caused by the abnormal high signal of the intake pressure sensor. The vacuum hose on the suction pressure sensor has a weak vacuum suction and the vacuum is the root cause of the above fault. The throttle valve was examined. , remove the throttle check sensor vacuum source area, between the throttle body and manifold block containing asbestos gasket seal, under the high temperature of the body and engine oil steam erosion, asbestos pad is not part of the pin swelling layer, blocking the narrow vacuum source channel, the cold machine asbestos pad swelling degree reduction, the fault disappeared. After this part of the spare gasket is cut off, the test car after reloading, the failure will be eliminated. (2) troubleshooting with waveform method Engine failure, sometimes intermittent fault, sometimes not, difficult to use data flow analysis and judgment. In the electronic control system, many sensors and actuators are represented by voltage, frequency or other digital form. In the actual operation of the engine, it is difficult to detect problems from these changing Numbers because of the rapid changes in the signals. However, the waveform shown in the oscilloscope can detect the small and discontinuous changes in the fault. It use of electronic-controlled engine work normally when the various sensor signals (including the crankshaft position sensor, camshaft position sensor, oxygen sensor signal and certain types of signals, the fuel injector air flowmeter, idle speed motor control signals, etc.) described by the waveform figure compared with a fault waveform figure, if there is abnormal, indicates the signal control circuit or component itself out of the question. The waveform analysis can show that the failure to repair is a kind of waveform so that you can see the real existence of the fault, and you can also know whether the fault is actually ruled out by analyzing it. The waveform analysis is used in the fault diagnosis and maintenance of automotive electronic control system, and the main application method has two aspects: one is to determine the operation of the whole system. The second is to determine whether an electrical appliance or circuit is out of order when the entire state is running normally. The most and most effective place for wave analysis is the analysis of the signal waveform of oxygen sensor. It can diagnose the failure of vacuum leakage, ignition and oil injection imbalance by analyzing the waveform of oxygen sensor. For example, a Shanghai santana 2000 sedan, which has more than 80, 000 kilometers, has a slow, unstable engine and sometimes a tempering phenomenon. In line with the principle of simplicity and complexity, the ignition coil, high voltage line, spark plug and distributor are inspected first, and the throttle valve, intake manifold and fuel injector are cleaned, and the failure is not ruled out. According to the fault phenomenon, the ignition system is examined by the waveform analysis method, especially the inspection of ignition timing. Use F98 oscilloscope test ignition system, waveform display without exception, the ignition system is normal, with king of decoder check, the fault code 0561, its meaning is mixture mismatch, this may be the cause of the failure. The testing of the santana mixture is based on an oxygen sensor. Using the F98 oscillograph to detect the oxygen sensor signal, the signal voltage is found at over 600mV, sometimes under 100mV, and there is no law in a certain range. The information detected by oxygen sensor is mixed. The reasons for the excessive mixture are: high oil pressure, long pulse width and incomplete combustion. When the oil pressure is detected, the idle speed is 0.25 MPa, and the acceleration is 0.29 MPa, indicating that the oil pressure is normal. Using the F98 oscilloscope to detect the pulse width of the first cylinder as 4.3 ms and sometimes 1.73 ms, it appears that the oil pulse width is not normal. Test two, three cylinder also have similar circumstance. Check the fourth cylinder, pulse width of 3.3 ms, sometimes up to 12 ms, can be obtained from the above data show the car fuel injection completely out of control, and overall injection quantity variable is causing the main reason for the fault code 0561. The reasons for the abnormal oil injection in the fourth cylinder are: intermittent grounding of cable bundles, bad computer ECU, and poor computer bonding. Therefore, careful examination of the wire harness and so on, no abnormality was found, which is the computer ECU problem. Replacement of the new ECU fault is also ruled out.
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