If the gearbox does not pay attention to maintenance, it is easy to fail. Once the automatic gearbox has problems, it is also very troublesome to repair it. The editor summarized the seven major faults of the gearbox, all of which are very difficult problems!
1. The car cannot run
II. Impact on starting or driving
3. Late arrival, dead arrival, and impact
4. Vehicles can't afford to run
Failure situation: the vehicle cannot run, including the absence of high speed, that is, no matter how it runs, the vehicle cannot reach a speed range of 100 km/h. The speed is very slow, that is, the accelerator is very heavy, but the vehicle is still slowly speeding up, the reaction is poor, and the feeling of being smooth is lacking. This situation also includes the slow speed of the engine, that is, the speed of the engine does not come up and the speed is fast but the speed is not fast.
Therefore, this is a very complicated problem. The normal test standard is that the vehicle starts and steps on the accelerator pedal appropriately. The engine speed increases smoothly and the vehicle accelerates, generally around 2500 revolutions, when the vehicle speed is between 25-30 kilometers, the automatic gearbox enters the first shift, and the engine speed gradually picks up when it falls behind properly. At the same time, the vehicle speed is obviously accelerated, and the second shift is made when the vehicle is 40 kilometers, after the gearbox enters the third gear, the speed will be further accelerated, and it will enter the high-grade position of the gearbox in the speed range of 60 kilometers. During the process of upgrading, the engine will be appropriately backward and lifted again, no idling, no slipping phenomenon.
Generally, when a vehicle with an engine displacement of about 2.0 is running smoothly, the speed of the engine at 2500-3000 RPM can reach 100 kilometers per hour. If the speed needs to be further increased, the engine speed needs to be increased synchronously. If the engine refueling is very stuffy and not smooth, it generally means that the engine needs to be repaired. If the engine acceleration is strong, it means that the internal gear of the gearbox is wrong, the clutch is burned, and the button changer has mechanical failure, etc.
V. Engine idling
Engine idling usually occurs in two situations:
First, when the vehicle is stationary, the engine idling suddenly occurs, and the speed slows down and returns to normal. This situation generally shows that the gearbox suddenly drops from high-grade to low-grade in a short period of time, the problem may be in the control system or heat dissipation system, and the gearbox itself has no problem.
The second is that there is a short slip idling phenomenon in the process of acceleration or in the process of shifting gears. The intuitive feeling is that the latter is not as powerful as the former, but actually it is exactly the opposite, most of the problems of the latter are in the clutch and other related links in the gearbox. When dealing with the problem, the gearbox should be completely disassembled and overhauled, and the time cost is much more than that of the former.
VI. High engine speed during driving
This problem also includes two situations: the constant speed during smooth driving and the speed during speed-up:
I. The speed is high in the smooth process, which is easier to test. For example, a vehicle with an engine displacement of 2.0 can reach 100 kilometers at 2600 revolutions at ordinary times, if you often need 3000 revolutions or more to reach 100 kilometers for a period of time, it means that there is a fault, generally, this kind of failure is caused by the high-speed gear failure of the gearbox or the internal locking clutch failure of the button changer, and the gearbox needs to be repaired immediately.
Second, the speed is high during the speed-up process. This fault test is a bit complicated, because in the speed-up process, the rise of the engine speed is closely related to the accelerator pedal owner, for example, a normal Passat engine can speed up the vehicle when its body speed reaches 2500 rpm in the case of small throttle, but the engine will increase to 5500-6000 rpm in the case of full throttle, such a huge contrast is controlled by the fuzzy logic of the electronic control system of the gearbox, so this standard needs a certain professional level to be completed.
VII. Abnormal noise of transmission
Fault condition: exceptional sound is called abnormal sound in the maintenance industry. In the process of automobile operation, there is abnormal sound in the common automatic transmission, and there is abnormal sound in the automatic transmission when the car is running, and the abnormal sound disappears after parking for gear.
There are four main reasons:
1. The oil pump produces abnormal sound due to wear or even low or high oil surface height of automatic transmission;
2. Torque converter abnormal sound caused by damage such as lock clutch and jockey pulley unidirectional overrunning clutch;
3. Abnormal sound of planetary gear mechanism;
4. Abnormal noise of shift actuator.
Solution:
1. Check The Automatic Automatic transmission fluid oil surface height. If it is too high or too low, it should be adjusted to the correct height.
2. Raise the car lifting jack, start the engine, and check the parts and moments where the automatic transmission produces abnormal sound in neutral, forward, reverse, etc.
3. If there is always continuous abnormal sound in the front of the automatic transmission in any gear position, it is usually the oil pump or torque converter abnormal sound. For this, the automatic transmission should be disassembled and inspected to check whether the oil pump is worn, is there a large amount of friction powder within torque converter. If there is any abnormality, replace the oil pump or torque converter.
4. If the automatic transmission has abnormal sound only in driving, and there is no abnormal sound in neutral, it is the abnormal sound of planetary gear mechanism. In this regard, the automatic transmission should be decomposed, and the parts of the planetary gear mechanism should be checked for wear marks, gear fracture, unidirectional overrunning clutch wear, lag, bearing or thrust washer damage. If there is any abnormality, it should be replaced.
