Mercedes-Benz E300 idles too low and shakes severely after starting

Q: A Mercedes-Benz E300 has been maintained at a 4S shop. Recently, the idle speed is too low and the shaking is severe after the vehicle is started. The vehicle can only return to normal after warming up for about 15 minutes. The throttle valve has been cleaned and the ignition coil has been replaced at the 4S shop, but the vehicle fault has not improved significantly. At the community beauty shop, the technician used a carburetor cleaner to spray and clean it from the front of the throttle valve when the engine was running. After spraying a bottle and a half of the cleaner, the engine was stuck. The starter made a “clicking” sound when starting, the engine did not run, and the engine could not be turned with the help of tools in neutral. What’s going on?

A: This means that the engine intake duct of the vehicle is seriously carbonized. When the carburetor cleaner is used to quickly flush the intake duct, large pieces of carbon deposits may fall off and enter the intake valve or cylinder, which cannot be discharged for a while, resulting in the failure of the piston to compress and cause the engine to stagnate. At this time, the engine may be damaged and needs to be disassembled, cleaned and inspected to eliminate hidden dangers. Generally, the damage to the engine can be seen by disassembling the cylinder head. A special note here is that when cleaning carbon deposits without disassembly, you must use a good product that can melt and decompose the carbon deposits, and burn the carbon deposits, turning them into smoke for discharge.