汽車頻繁強制降擋、行駛頓挫，竟是因為燃油濾清器故障汽車在高負荷的工況下，為了保證動態性能，自動變速箱通常會按需自行強制降擋。下面就讓
濟南奧迪汽車保養人員來詳細講解這個問題吧。
The frequent forced downshifts and bumps of the vehicle are actually due to the fuel filter failure. In order to ensure the dynamic performance of the vehicle under high load conditions, the automatic transmission will usually automatically force downshifts as required. Let's let Jinan Audi car maintenance personnel explain this problem in detail.
維修人員駕車路試，可以感到車輛的動力偏弱，在試圖讓車輛正常提速時，不僅加速偏慢而且還會強制降擋，行駛頓挫感是在降擋時出現的。連接診斷儀檢測車輛發動機和變速箱系統，并未發現任何故障碼。行車時讀取變速箱數據，油壓、油溫、輪速、輸出轉速等數據也都正常，由此懷疑是發動機存在動力輸出不足的問題。
Maintenance personnel can feel that the power of the vehicle is weak during driving test. When trying to increase the speed of the vehicle normally, they will not only accelerate slowly but also force downshift. The feeling of driving stumbling occurs during downshift. Connect the diagnostic instrument to test the engine and transmission system of the vehicle, and no fault codes are found. Read the transmission data while driving, and the oil pressure, oil temperature, wheel speed, output speed and other data are normal. Therefore, it is suspected that the engine has insufficient power output.
回到維修廠，為發動機接入燃油壓力表，查看燃油壓力數據。起動發動機，怠速時燃油壓力正常。踩下加速踏板，讓發動機轉速升高，燃油壓力也相應有所上升。但是當轉速升高到3000r/min左右時，燃油壓力表的指針就出現了抖動且壓力不再上升，發動機運轉吃力。顯然，當發動機的轉速上升后，燃油壓力無法滿足需求，供油不足，造成發動機難以輸出充足動力。
Return to the repair shop, connect the fuel pressure gauge for the engine and check the fuel pressure data. Start the engine and the fuel pressure is normal at idle speed. Press the accelerator pedal to increase the engine speed and the fuel pressure. However, when the rotation speed rises to about 3000 R / min, the pointer of the fuel pressure gauge vibrates and the pressure does not rise any more, which makes the engine difficult to operate. Obviously, when the engine speed rises, the fuel pressure cannot meet the demand and the fuel supply is insufficient, which makes it difficult for the engine to output sufficient power.
通過上述檢測得知，發動機在轉速升高后，會因為供油不足而動力受限，這時自動變速箱就會強制降擋。正常情況下，強制降擋之初，發動機會補油提高發動機轉速，平衡當前輪速和變速箱輸出轉速的差異，避免出現頓挫。
According to the above detection, after the engine speed increases, the power will be limited due to insufficient fuel supply, and the automatic transmission will be forced to downshift. Under normal circumstances, at the beginning of forced downshift, the engine will supplement oil to increase the engine speed, balance the difference between the current wheel speed and the transmission output speed, and avoid setbacks.
然而，當前發動機得到的燃油量不足，無法拉高轉速，就造成了強制降擋后車輛出現明顯的頓挫感。導致燃油壓力低、發動機供油不足的主要原因有燃油泵故障、燃油濾清器堵塞、燃油管路堵塞，以及燃油壓力調節器異常泄壓等。
However, the current engine does not get enough fuel and can not pull up the speed, which causes the vehicle to appear obvious setback after forced downshift. The main causes of low fuel pressure and insufficient fuel supply to the engine are fuel pump failure, fuel filter blockage, fuel pipeline blockage, and abnormal pressure relief of the fuel pressure regulator.
本著先簡后繁的檢查原則，維修人員決定首先舉升車輛查看燃油濾清器。檢查發現，車上的燃油濾清器比較新，應該是新換的，但從外觀看不是正品。將燃油濾清器拆下，發現是沒有商標的劣質產品。為車輛換上正品部件后起動發動機，燃油壓力恢復正常。
Based on the principle of simple inspection before complicated inspection, the maintenance personnel decided to lift the vehicle first to check the fuel filter. The inspection found that the fuel filter on the car was relatively new and should have been replaced, but it was not genuine from the appearance. When the fuel filter was removed, it was found that it was a poor product without a trademark. After replacing the vehicle with genuine parts, start the engine and the fuel pressure returns to normal.
隨后駕車外出路試，車輛加速性能正常、動力充沛，頻繁強制降擋和頓挫的情況也不再出現，故障排除。汽車頻繁強制降擋、行駛頓挫維修總結劣質燃油濾清器，可能在燃油流通量、泄壓閥激活閾值等方面與正品存在較大差異。
After driving out for road test, the acceleration performance of the vehicle is normal and the power is abundant. The frequent forced downshift and setback are no longer occurred, and the fault is eliminated. Summary of frequent forced downshifts, bumps and maintenance of vehicles poor quality fuel filter may be greatly different from the genuine one in terms of fuel flow and activation threshold of pressure relief valve.
Under heavy load conditions such as vehicle acceleration, it is necessary to increase the fuel supply, and the fuel is blocked or relieved at the inferior filter, resulting in insufficient fuel supply for the engine and the speed cannot be increased. You can visit our website for more information http://www.liangshuijing.cn Consult and understand.
