In many cases of automatic transmission maintenance, shift impact is common. Automatic transmission has been used for a long time, and shift impact often occurs. If this happens, it must be repaired in time to avoid danger in driving.

车主黄先生：我的车已行驶25000，我发现冷车启动到热车，当发动机转数达到1000，刹车踩紧时，挂D挡起步时阻力较大，挂R挡时有较大冲击感。请问这是什么原因？

Owner Mr. Huang: my car has driven 25000 km. I found that when the cold car starts to the hot car, when the engine speed reaches 1000 and the brake is pressed tightly, the resistance is greater when I start in D gear, and there is a greater sense of impact when I shift into R gear. What is the reason?

出诊：自动挡车型，理论上挂挡都会有冲击感，D挡与R挡一样。若两者冲击感不同，则有

Expert visits: in theory, automatic models have a sense of impact when they are in gear. D gear is the same as R gear. If the impact of the two is different, there is a difference

车主黄先生：我的车已行驶25000，我发现冷车启动到热车，当发动机转数达到1000，刹车踩紧时，挂D挡起步时阻力较大，挂R挡时有较大冲击感。请问这是什么原因？

Owner Mr. Huang: my car has driven 25000 km. I found that when the cold car starts to the hot car, when the engine speed reaches 1000 and the brake is pressed tightly, the resistance is greater when I start in D gear, and there is a greater sense of impact when I shift into R gear. What is the reason?

出诊：自动挡车型，理论上挂挡都会有冲击感，D挡与R挡一样。若两者冲击感不同，则有可能是发动机前后防震垫损坏层度不同和变速箱内部故障造成的。另外，较大冲击感有可能是发动机转速太高造成的，变速器的动力传递是由发动机转速决定的。

Expert visits: in theory, automatic models have a sense of impact when they are in gear. D gear is the same as R gear. If the impact feeling of the two is different, it may be caused by the different damage layers of the front and rear shock pads of the engine and the internal fault of the transmission. In addition, the greater impact may be caused by the high engine speed, and the power transmission of the transmission is determined by the engine speed.

异响

Abnormal noise

车主赵先生：近几天，我的车在凉车启动时，感觉在A柱附近有嗒嗒的声音，特别是在颠簸路段，声音特别大。车热了之后，声音消失，请问这是什么原因？是不是气温太低引起的呢？

Owner Mr. Zhao: in recent days, when my car starts in the cold, I feel that there is a rattling sound near the A-pillar, especially in the bumpy road. After the car is hot, the sound disappears. What's the reason? Is it caused by the low temperature?

出诊：如果响声与温度变化有关，就应属发动机配气机构的冷响，这种冷响是随汽车行驶里程(5-10万)的增加，而逐渐出现的，也是正常的自然磨损过程中出现的异响。另外，根据赵先生所说的情况，颠簸路段，声音特别大，则有可能是A柱附近部件松动造成的，与温度无关。

Expert visit: if the noise is related to temperature change, it should be the cold noise of engine valve train. This kind of cold noise gradually appears with the increase of vehicle mileage (50000-100000 km), and it is also the abnormal noise in the process of normal natural wear and tear. In addition, according to what Mr. Zhao said, if the noise is particularly loud on bumpy road sections, it may be caused by loose parts near the A-pillar, which has nothing to do with the temperature.