What are the reasons for severe engine shaking in a new car?

[LeDaniela]

The reasons for severe engine shaking in a new car are: 1. Aging or loosening of engine mounts; 2. Engine misfire; 3. Severe carbon buildup in the engine; 4. Tire bulges or wheel hub deformation; 5. Intake pipe or EGR valve leakage; 6. Loose chassis components. The solutions for engine shaking in a new car are: 1. Read fault codes or data streams to eliminate sensor failures; 2. Check if the exhaust gas recirculation valve has issues; 3. Inspect spark plugs, high-voltage lines, ignition coils, fuel injectors, timing marks, fuel pump pressure, and cylinder pressure; 4. Check if the idle speed control valve has problems, and clean the throttle body and idle speed control valve.

[LaKaden]

When I first got my new car, the cold start was so rough that the steering wheel vibrated. Later, I found out that the ignition coil connector wasn't securely fastened. The 4S technician used a diagnostic tool and discovered intermittent misfires in the third cylinder, which stabilized after reconnecting it. During transportation, some connectors on new cars can indeed become loose. Especially if the spark plugs weren't torqued to specification during assembly—even being half a turn off can cause uneven combustion of the air-fuel mixture. Additionally, I recommend checking the fuel system. A friend once filled up with 92-octane gas that had too much gum content, causing slight clogging in the fuel injectors and leading to rhythmic vibrations. Switching to 95-octane and running two tanks cleared it up. Regularly driving on highways to clean out carbon deposits is actually quite necessary.

[HadleyLee]

Last month, I accompanied a colleague to address the issue of a new car shaking. The 4S dealership directly replaced the engine mount rubber pads, which resolved the problem. If the rubber vibration dampeners are misaligned during assembly on the production line, engine vibrations can be directly transmitted to the cabin. Remember to have them check the torque values of the engine mount bolts, as new cars often haven't been properly broken in. Also, a quick reminder: if the steering wheel shakes severely during auto start-stop, it might be due to a stuck generator one-way pulley causing sudden changes in crankshaft load, which is more common in hybrid vehicles. It’s also quite important to inspect cylinder conditions with an endoscope during maintenance.