The speed is high, but the speed is rising slowly. What's the matter?
This is a classic problem. I believe many car owners have met it. Don't think the old car will have this problem. The new car will, of course, only if it is equipped with a new driver. Don't wait until you run at high speed, press the accelerator hard, the speed is 3 or 4000, but the speed is still 8 or 90km / h, so it's useless to be depressed at this time. So get it up.
We can first see how the power of the vehicle comes from: first, we step on the accelerator → the engine computer controls the intake and injection according to the accelerator signal → gasoline and air enter the cylinder for mixing → the spark plug ignites the mixture to push the piston to move → drive the crankshaft to rotate, so the engine has power.
Then the power passes through the clutch, gearbox, transmission shaft, differential and half shaft as shown in the figure below and reaches the driving wheel, so that the vehicle moves and produces speed.
The engine speed can be increased. Generally speaking, the engine is normal. Some friends may say that there is a lack of cylinder, but the lack of cylinder will cause the engine speed and the speed of the car to decrease, rather than increase the speed, and the speed is not very static. So the problem probably lies in the transmission parts, and the function of the differential mainly provides different power distribution when turning. It doesn't matter much.
Therefore, the causes of high speed and low speed are as follows:
1. Transmission / clutch failure:
a. Too little oil in the gearbox results in too low oil pressure, which leads to slipping of the clutch and brake;
b. Friction plate of clutch or brake is worn or ablated, causing slipping;
c. The oil pump, oil circuit and sealing ring of gearbox are damaged or leaked, resulting in low oil pressure and slipping;
d. One way clutch slipping;
e. Lock up clutch failure, such as lock in a certain gear does not upshift;
f. Gearbox computer failure;
g. Gearbox valve body failure;
2. Transmission shaft fault: for example, BMW M3 / M4 has a recall of the transmission shaft. Long term high load use may cause the transmission shaft flange to come out, causing the transmission shaft to slip, unable to accelerate.
3. Axle shaft fault: similar to the transmission shaft, the axle shaft is connected to the drive wheel. Once the axle shaft slips, the power acting on the drive wheel will drop a lot, and the speed will be difficult to increase naturally. At this time, the driver must step on the accelerator more deeply, and the engine speed will be high.
In addition to the above main fault causes, there are many funny misoperations in reality, which may also lead to similar phenomena, such as:
1. Be limited by oneself without knowing;
2. Didn't notice that the crew switched to DS gear, delayed shifting;
3. New car, 4S forgot to release the transport mode for you;
4. Forget to put down the handbrake. Don't laugh. Someone has run hundreds of kilometers with the handbrake.