Mercedes e300 idling up and down.

The problem of unstable engine idle speed is mostly caused by carburetor and gasoline injection device, that is, the idle speed of the oil supply system is improperly adjusted, and the fuel that can be normally supplied to the engine is too small, thus making the engine output torque too small. In this case, you can readjust the idle speed adjusting screw, which will immediately make the engine run smoothly at idle speed. If you feel trouble, you can go to the repair shop and ask the maintenance staff to do it for you. In addition to the fuel supply system, if the spark plug fails, it will also lead to unstable engine idle speed. Once the spark plug of a cylinder is abnormal, the idle speed will fluctuate greatly immediately. Check the spark plug of each cylinder. You can unplug the high voltage line of each cylinder in turn, and it is easy to find out the faulty spark plug. In addition, if the air intake system is blocked or too dirty, it will also make the engine idle unsteadily. At this time, the carburetor cleaning agent can be injected into the carburetor.