汽车故障诊断与排除的基本方法.docx

1、汽车故障诊断与排除的基本方法汽车故障诊断与排除的基本方法Core tip: the basic method of automobile fault diagnosis and troubleshooting is the basis of troubleshooting and the effective means to improve the efficiency of vehicle maintenance. In order to diagnose faults quickly and accurately, it is necessary to understand the bas

2、ic thinking and methods of diagnosing faults, and to master the basic requirements and methods for troubleshooting. First, the basic thinking and methods of fault diagnosis, the diversity of vehicle fault phenomena and the complexity of the cause, lead to the diversity and uncertainty of the thinkin

3、g and methods of fault diagnosis.The basic method of automobile fault diagnosis and troubleshootingThe correct diagnosis of the fault location is the basis of troubleshooting, but also an effective means to improve the efficiency of vehicle maintenance. In order to diagnose faults quickly and accura

4、tely, it is necessary to understand the basic thinking and methods of diagnosing faults, and to master the basic requirements and methods for troubleshooting.I. Basic Thinking and method of diagnosing faultsThe complexity and diversity of automobile fault phenomenon reason, caused the diversity of i

5、deas and methods of fault diagnosis and uncertainty, but on the whole, the basic ideas and methods should be based on the first mechanical electronics, first special, easy to difficult, simple to complex primary diagnosis.1, the basic process of diagnosing faultsThe basic process of diagnosing autom

6、obile faults usually includes the following steps: inquiring the situation, reproducing the fault phenomenon, determining the fault characteristics, analyzing the cause of the trouble, drawing up the inspection scope and finding the fault point.Ask about the situation. Mainly to the driver to unders

7、tand the vehicle before the failure of some basic information, such as vehicle mileage, vehicle maintenance and repair, the use of vehicles at ordinary times, before the failure of the special phenomenon.Reproduce the fault phenomenon. By means of a certain method and technical means, the phenomenon

8、 of failure will be manifested, such as in-situ launch, road test, etc. For continuous reproduction of fault, fault phenomena are generally easier; but some of the intermittent fault, because the fault occurs only in a particular environment, so the need to reproduce by means of fault simulation env

9、ironment, such as through vibration, heating, water, or load (load) etc.Determine fault characteristics. The fault phenomenon caused by a fault is usually characterized by its specific fault, that is, fault characteristics, and it is very important to find out the fault characteristics and reduce th

10、e diagnostic range and diagnose the fault quickly. For example, a unit of SX2190 commercial vehicles, in the execution of the task, suddenly appeared vehicle underpowered, the engine running weak, until slow flameout. Driving on the phone reflects: hit the starter, no car, using electric fuel pump e

11、xhaust, found a large number of bubbles discharged, air discharged after the smooth start, but after a period of mileage, the fault occurred again. To further understand the situation that this car since two level maintenance after traveling around 5000km, which found no such fault, but the recent d

12、ifficult starting, generally according to the electric fuel pump, and the electric fuel pump and found no leakage phenomenon. The diesel filter was cleaned two days before the failure. From the basic information reflected by the driver above, it can be determined that the car has many fault phenomen

13、a, such as difficult starting, engine running, vehicle power shortage and engine flameout,But what fault can represent fault characteristics? It is clear that the engine itself is the most representative of the breakdown characteristics of the car.Analyze the cause of the trouble. According to the s

14、pecific structure and fault characteristics of the car, the cause of the trouble is analyzed. In the example above causes the engine to stall.A. tank without oil.B, the diesel line is not sealed and enters the air.C. diesel filter and diesel pipe blocked.Core tip: the basic method of automobile faul

15、t diagnosis and troubleshooting is the basis of troubleshooting and the effective means to improve the efficiency of vehicle maintenance. In order to diagnose faults quickly and accurately, it is necessary to understand the basic thinking and methods of diagnosing faults, and to master the basic req

16、uirements and methods for troubleshooting. First, the basic thinking and methods of fault diagnosis, the diversity of vehicle fault phenomena and the complexity of the cause, lead to the diversity and uncertainty of the thinking and methods of fault diagnosis.D. there is water in the fuel.E. oil pum

17、p does not work.F. injection pump connection plate fixed bolts loose.G. fuel injection pump handle rod fall off.H. the oil outlet valve and needle valve of the same cylinder are not sealed.Since the car fault is slow flameout, so F.G can be excluded (F.G caused by sudden flameout); the car engine po

18、wer is not decreased, D can be excluded; the car can still work for a period of time, e can be ruled out; according to the electric fuel pump can be in a car, and the failure occurred two days before the filter cleaning. A and C can be ruled out; according to the electric fuel pump not found leaking

19、 position, B can be ruled out: so the rest of the h with a cylinder valve and needle valve and vice vice seal should be the cause of the failure.Formulation of inspection scope. Determine the scope, procedure and method of the inspection in accordance with the conclusions of the failure analysis.To

20、find the point of failure. According to the scope of inspection, the method of subsection, fixed-point or point by point inspection is adopted. At the time of inspection, the technical standards of the checked parts should be well known, and at the same time, the inspection should be avoided.2 analy

21、ze the main points of the troubleAnalysis of fault reasoning is essentially a process of thinking, the process for the length of time, the reasoning is correct or not, is affected by many factors, such as the accumulation of experience and knowledge, using the structure of automobile diagnostic inst

22、rument by skilled degree and quality of thinking clarity, flexibility, sensitivity and stability, psychology the quality of health, will be different degrees directly or indirectly influence the speed and quality of reasoning.In the process of fault analysis, experience is a very important factor, e

23、specially for those who have been engaged in single vehicle type and fixed system maintenance for a long time. The speed and accuracy of common fault analysis are very high. The reason, on the one hand, is due to the long experience in the accumulation of direct experience is very rich, on the other

24、 hand, it also benefits from its continuous summary and improvement. In addition to direct experience, through case study and dissection, it is an effective way to obtain maintenance experience. This is called indirect experience, and indirect experience is of great help to improve the quality of fa

25、ult analysis. Whether it is direct experience or indirect experience, in general, it can play a positive role in the fault analysis process,That is, experience guides thinking quickly and accurately to find fault points. For example, if fault code display engine, should first check the fault code di

26、splay content, this experience may make you win all the time, in the work to strengthen the experience if things go on like this, in your mind, and gradually solidified, become a mindset. However, if one day you find that this experience is not working, and when you have checked the circuit accordin

27、g to the experience, and replaced the electrical components, the fault still exists, that is, experience has played a misleading role. Instead, it becomes a barrier to correct thinking. So the experience is valuable, but is not limited to specific conditions method.It is hard to imagine a doctor who

28、 knows little about the structure of the human body and can quickly and accurately diagnose the cause of the disease. Also, the basic knowledge of automobile structure knowledge is also essential vehicle maintenance, in addition to the five base, namely the basic structure, basic function and compos

29、ition of the basic control relation, basic principle, basic performance parameters, the structural features of different types of car should also be understood that the specific structure of the fault of the vehicle to be aware, otherwise most of our preparation became a false, Yong Zhi shui. It sho

30、uld be emphasized that, with the increasing application of electronic technology in the car more widely, the electronic control system software upgrade faster, more and more wide range of control, control precision is more and more high, so the task is very important to study the control system soft

31、ware, hardware and software to match knowledge the hardware structure of the corresponding software versions are not the same.In the process of fault analysis, it is necessary to use diagnostic instruments and equipment parameters or performance testing necessary, commonly used instruments and equip

32、ment in addition to be able to use, we should pay attention to the detection accuracy of calibration instrument, the equipment itself, to prevent the emergence of large detection error, which brings difficulties to fault analysis.Core tip: the basic method of automobile fault diagnosis and troublesh

33、ooting is the basis of troubleshooting and the effective means to improve the efficiency of vehicle maintenance. In order to diagnose faults quickly and accurately, it is necessary to understand the basic thinking and methods of diagnosing faults, and to master the basic requirements and methods for troubleshooting. First, the