What Causes the Left-Right Shaking of a Mercedes-Benz at Idle?

[VanDelaney]

Mercedes-Benz left-right shaking at idle can be attributed to the following reasons: Engine Mount Issues: For instance, if the engine mounts are too dirty, aged, or damaged, they can cause engine vibrations that transmit throughout the entire vehicle body. Resonance at Idle: For example, some cars may shake when the idle speed is stable at 700 RPM. In such cases, simply increasing the idle speed slightly can stop the shaking. Therefore, if all else fails, you can try adjusting the idle speed in D gear. Air-Fuel Mixture Problems: Among these, excessive carbon buildup in the throttle body and fuel injectors is the most common cause of shaking. On one hand, carbon deposits tend to absorb fuel vapor, leading to a leaner air-fuel mixture. Once the carbon deposits absorb enough fuel vapor, the car returns to normal operation. This is one reason why the car shakes when cold but stops shaking once it warms up. On the other hand, carbon deposits can cause blockages, such as clogging the fuel injectors, reducing the amount of air-fuel mixture entering the cylinders or causing poor atomization, which can also lead to shaking.