In recent years, due to increasingly stringent requirements on vehicle safety performance and emissions, the Ministry of Transport has revised the original "JT201 Specification" and formulated the "carTechnical Specifications for Maintenance, Testing and Diagnosis" is the new national standard GB18344-2001, the purpose is to further standardizecar repairThe maintenance and inspection behaviors in the industry are well-documented, so that they can be fully implemented
The maintenance system of "regular inspection, mandatory maintenance, and on-demand repair". In the actual implementation process, especially for cars with electronically controlled fuel injection systems, there are still problems such as not knowing how to start, failing to diagnose according to procedures, and human failures. I will talk about how to implement EFI engines in accordance with the new national standard. Secondary maintenance.
1. Recognize the importance of secondary maintenance
Car secondary maintenance is the highest level of maintenance specified in the car maintenance system, and it is also the most important maintenance. It will directly affect the normal operation of the car during the secondary maintenance interval. At present, my country's cars have generally adopted electronically controlled fuel injection systems, which have greatly improved the power and economy of car engines, and in particular, the emission purification performance has been effectively improved. To ensure that these performances are brought into full play, the new national standard clearly stipulates that the I/M system of in-use vehicles must be strengthened, that is, the inspection/maintenance system. For electronic fuel injection vehicles, secondary maintenance is the key. It is not only a comprehensive and thorough maintenance of the vehicle, but also a regular maintenance behavior; it is an important maintenance method to maintain the good performance of electronic fuel injection vehicles, and maintenance Quality has a great influence on the service life of a car. It can be seen that doing a good job in the secondary maintenance of EFI vehicles is very important.
2. Strictly abide by the secondary maintenance process
The secondary maintenance process specified in the national standard is shown in the figure:
Compared with the secondary maintenance process specified in "JT201", the GB18344 regulations are more detailed and clear, and are more in line with the development of modern automobile technology. This regulation emphasizes the importance of basic work before secondary maintenance, focusing on customer surveys and basic inspections.At present, most maintenance personnel immediately go to get a digital multimeter orDetector, Blindly measuring, not paying much attention to visual inspection and basic inspection, causing detours when judging faults abound. From this point of view, performing maintenance in accordance with procedures and strengthening the basic work of electronically controlled vehicles can have a multiplier effect in diagnosing faults.
This process emphasizes that non-disintegration testing must be carried out before secondary maintenance operations, and the items required for additional operations are determined by the test results, excluding human subjective factors, and following the principle of condition-based repair. During maintenance, it is necessary to strengthen process inspection, find and solve problems in time, guarantee the quality of maintenance from time to time, and achieve the real purpose of secondary maintenance. Pay attention to the completion of the inspection to carefully fill in the factory certificate and technical files. This procedural quality management of pre-maintenance inspection, maintenance inspection, and post-maintenance inspection reflects the spirit of the ISO9000 quality system standard.
3. Understand the requirements of the new national standard for secondary maintenance
Like other vehicles, EFI vehicles must meet the following requirements when performing secondary maintenance:
(1) When the secondary maintenance test items are tested,
The precision of the instrument used for this test item must meet the relevant requirements.There is a one-to-one correspondence between the accuracy of the testing instrument and the testing result, which directly affects the scope and extent of maintenance operations.Maintenance equipmentThe maintenance is also very important.
(2) The technical requirements of the secondary maintenance and testing items should refer to the relevant national technical standards or the original factory requirements. The country has unified technical standards for vehicles, such as safety, braking, environmental protection, etc. must comply with national regulations. In addition, it should be based on the "original factory requirements" that the maintenance manufacturer or individual should pay attention to the collection of vehicle maintenance data. This is especially important for EFI vehicles, because there are many types of EFI vehicles and the control forms are various, otherwise it is impossible to start secondary maintenance operations.
(3) The basic operation items of the secondary maintenance should be completed without compromise in accordance with the items and requirements specified in the new GB18344-2001 standard. The vehicle must be maintained regardless of the technical status of the vehicle, embodying the principle of "mandatory maintenance" and promoting I The effective implementation of the /M system ensures that the technical status of vehicles is intact and strictly controls the emissions of in-use vehicles to meet environmental protection requirements.
(4) According to the test results, determine the secondary maintenance additional work items and work content for the purpose of eliminating the car failure, and restore the normal technical state of the car. Through the non-disintegration test, it can accurately evaluate the technical status of the car, determine the appropriate additional work items, and eliminate the hidden troubles of failure, thus embodying the maintenance technology management principle of "combination of technology and economy".
Due to the complex structure of EFI vehicles, improper maintenance operations will cause man-made failures, especially in terms of engine maintenance. You must also pay attention to the following points:
1) Prevent self-inductance transient voltage.existIgnition SwitchWhen it’s on, you can’t disconnect electrical devices, such as fuel injectors, computers,AccumulatorWait for the wiring of the equipment, otherwise it will burn out the computer andsensor; Do not use test lights to detect electrical devices connected to the computer; do not reverse the positive and negative poles of the battery, etc.
2) Prevent the influence of high temperature. Generally, the ambient temperature should not exceed 85°C, and the heating temperature of the paint should not exceed 80°C.
3) Prevent the interference of the magnetic field. Stereo speakers and radio facilities such as radio stations and telephones should be kept away from the computer.
4) Prevent vibration and moisture. Care should be taken when installing the computer and cleaning the car engine to prevent the computer from being unable to work normally due to large vibrations and water ingress.
5) Prevent static electricity. If you are testing a computer, it is best to bring a ground wire to operate, and do not burn out the electronic components of the computer due to the high static voltage of the human body.
4. Clarify the content of the secondary maintenance of EFI vehicles
The new national standard stipulates that the secondary maintenance content of EFI vehicles includes basic operation items and additional operation items. The basic operation items mainly include engine power, emission purification performance, electronic control fuel injection system, safety performance, chassis and other parts of the system, etc. In terms of work items, work content and technical requirements, there are detailed and clear regulations, a total of 35 items. Compared with the "JT201 standard", this content strengthens the maintenance of safety and emissions, and has a principled guiding role. Because there are more and more models of EFI cars, the structure is more and more complex, and the technical content is getting higher and higher. Therefore, in the maintenance process, the goal is to "eliminate faults and hidden dangers and ensure the perfect technical state of the car", and arrange reasonable arrangements based on actual conditions. contents of homework.
The additional work items are determined through testing and can be carried out together with the basic work items. The technical specifications shall be carried out in accordance with the requirements of the "Model Maintenance Manual".
5. Gradually master the detection and diagnosis methods for the secondary maintenance of EFI vehicles
Commonly used methods such as adjusting fault codes and using multimeters, data streams, waveform analysis and other methods to perform detection and diagnosis of EFI vehicle secondary maintenance. The scope of use and skills of these methods require special training and practice on a certain theoretical basis. Exercise can only be grasped initially, and it is necessary to continue to summarize in actual operation. In the past, the practice of dismantling cars wherever there are faults is not feasible in the maintenance of modern cars, especially on EFI cars. On the contrary, unexpected failures will occur due to the burning of electronic components due to the instantaneous excessive voltage. Therefore, in the diagnosis The failure of the automobile electronic control system must follow the procedure, pay attention to collecting the relevant technical information of the automobile, and proceed according to the requirements, forming a good car repair behavior, and improving the service quality of the auto repair industry.
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