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Repair of common faults of automobile electronically controlled engines

By, CoolMotor

• 2024-04-22
• 2 View

Repair of common faults of automobile electronically controlled engines

1. Line failure

During the operation of the automobile engine, various systems are connected by wires, such as sensors, actuators and electronic controllers. If a circuit failure occurs while the engine is running, it will inevitably cause the sensor detection signal to be blocked during transmission and cannot be sent to the ECU in time, and the ECU's instructions cannot be transmitted to the actuator, causing the engine to not operate normally, eventually leading to an accident. . Generally speaking, circuit faults in automobile electronically controlled engines are caused by factors such as loose wiring positions and poor contacts.

2. Component aging or performance degradation

An engine that is running for a long time will inevitably be exposed to high temperatures, which will cause wear and tear on the electronic components in it over time. This will inevitably cause problems such as component aging or poor operating performance, which will have an impact on the functionality of the electronic components and the overall performance of the engine. At the same time, if the inside of the engine is not cleaned regularly, the dirt and dust in it will also affect the operating status of the components.

3. Component breakdown

Component breakdown failure often leads to short circuit, usually because the internal voltage of the engine exceeds the normal value or the engine continues to run at high speed and overheats. If components such as capacitors or transistors in the engine break down and cause a short circuit, it is easy to cause a fault in the ignition system of the car's engine, and it is very easy to cause a failure to start.

2. Automobile electronically controlled engine fault diagnosis

The following tools are generally used to diagnose and repair common faults of electronically controlled engines:

① Jumper wire, a type of special wire, has different connectors at both ends and can be suitable for jumpers at different locations. It is generally used in the diagnosis and repair of circuit faults;

② Test lamp, which determines the circuit voltage according to the actual brightness of the lamp. It is generally used in the circuit inspection process of electronic control components;

③Digital multimeter has high measurement accuracy, strong anti-interference and wide application range. This instrument can be used in the measurement of resistance, voltage and current, and can accurately determine the main status of electronic control components;

④ Manual vacuum pump is a type of vacuuming instrument, which usually acts on the vacuum driving components in the engine electronic control system;

⑤Fuel pressure gauge to measure fuel pressure. Other common tools include injector cleaning equipment, oscilloscopes, and signal simulation testers.

3. Main points of automobile electronically controlled engine maintenance

The development and promotion of automobile fault self-diagnosis systems have made the troubleshooting and maintenance of electronically controlled engine faults easier to a large extent. Generally speaking, maintenance personnel can accurately determine the fault situation based on the fault code. In specific fault diagnosis, there are still some imperfections in determining fault phenomena based solely on fault codes. We should also conduct a comprehensive evaluation of the electronic system, so that we can find the fault problem more accurately. When diagnosing and repairing automobile electronically controlled engine faults, you must pay attention to the following points:

(1) After an electronically controlled engine fails, if it is a mechanical failure, empirical methods can be used to directly inspect and eliminate it.

(2) Before reading the fault code of the electronically controlled engine, a basic inspection of the engine should be carried out, that is, the basic idle speed and basic ignition timing should be detected and adjusted to ensure that the engine is in a suitable state for inspection. Reasonably adjust the basic inspection methods and steps according to the vehicle type. If during the actual inspection, specific requirements are given for the opening and closing status of additional electrical equipment, coolant temperature, radiator and cooling fan operation, the relevant maintenance information must be adhered to during the actual operation.

(3) When choosing a fault self-diagnosis system for troubleshooting, you should have an in-depth understanding of the detailed information of the vehicle model, such as the meaning of the fault code, the reading method, the basic parameters of the engine electronic control components, and the workpiece performance parameters. , which is the prerequisite for improving fault repair efficiency.

(4) The circuit of the electronically controlled fuel injection system is the same as other electronic circuits and has circuit characteristics, that is, voltage and resistance characteristics with its own operating characteristics. For example, there are different working voltages on each terminal of the ECU harness connector; there are different resistance values between each circuit controlled by the ECU and between the sensor and actuator terminals. Therefore, in the absence of a car-specific ECU fault detection instrument, you can choose a multimeter to measure the voltage value of each terminal of the ECU harness connector and the resistance value between each other, so as to initially determine the fault.

(5) When using a multimeter to test the ECU and control circuit, the specific maintenance data of the target model should be used. For example, the specific names and connection diagrams of the sensors and actuators connected to each terminal in the automotive engine ECU wiring harness connector, the standard voltage values of different terminals in various engine states, and the standard resistance values between each terminal, etc. Only by mastering the maintenance technical data of the vehicle model can the occurrence of human fault codes be avoided as much as possible. Another issue that should be paid attention to is that the ignition switch must be turned off before troubleshooting. If electronic components need to be replaced, the new components must be tested before replacement; when performing fault repairs, the fault phenomenon should first be confirmed, and then the fault location can be gradually found. and the cause, and finally take targeted maintenance measures. Many times there is more than one fault in an electronically controlled engine. After a certain fault is rectified, other faults will gradually surface. Therefore, it should be carefully and repeatedly inspected to ensure that the fault is completely eliminated.