How to solve the problem that the speed of freight cars can only reach 2000?

Because diesel is compression-ignition type, it has high efficiency and great torque. If the torque is large, the natural horsepower will be small, and the speed will not go up. Or the diesel engine is not suitable for high-speed operation. Energy conservation, large torque, speed will definitely not go up. God is fair, it is impossible to have the terrible torque of diesel engine and the terrible speed of gasoline engine at the same time.

First of all, the throttle controls the air intake of the engine. The more air intake, the higher the speed. There are two ways for throttle to control idle intake, one is through idle motor adjustment, and the other is through throttle itself adjustment. Your idle speed can be as high as 2000. It should be possible that there is something wrong with the idle air intake adjustment.

If your car is a cable accelerator, there must be an idle motor. You can remove it to check whether the head of the idle motor is worn or loose, which will lead to problems in air intake regulation.

If your car is an electronic throttle, it is usually the throttle itself that regulates the air intake. If there is something wrong with the adjusting mechanism or the throttle valve plate is stuck, if there is a diagnostic instrument, you can check whether the throttle opening value is too large at high idle speed, or you can play more aggressively, that is, remove the intake hose at high idle speed and directly look at the throttle valve plate opening.

But it takes some experience. If it's the throttle, it needs to be repaired or replaced. I suggest that if you have strong hands-on ability, you can dismantle and repair it yourself, because there is nothing too precise in the structure itself, and most of them are contact wear or mechanical problems.

Followed by intake manifold pressure.

Some cars use the intake manifold pressure sensor as the main reference to judge the intake air volume, because vacuum will be generated in the intake manifold when the engine inhales. At this time, if you step on the accelerator, the throttle opening will increase and the vacuum of the intake manifold will decrease, so the system can detect that the driver stepped on the accelerator. If there is air leakage between the intake manifold and the throttle, the absolute pressure of the intake manifold will also increase, which will make the computer mistakenly think that you stepped on the throttle, and then control the injector to increase the fuel injection quantity and improve the vehicle speed.