What Causes Engine Shaking at Idle in New Cars?
3 Answers
The causes of engine shaking at idle in new cars are: 1. Severe engine carbon buildup. A common reason for car shaking is excessive dirt in the throttle body or carbon buildup in the fuel injectors. The solution is to clean the fuel system and check the idle air control valve for carbon deposits, which should be cleaned if necessary. 2. Ignition system issues. Poor performance of the ignition system or faulty spark plug firing can also lead to such symptoms. The solution is to check if the spark plugs have excessive carbon buildup and replace them if needed. 3. Unstable fuel pressure. If you have already cleaned the engine carbon deposits, throttle body, replaced gaskets and spark plugs, but still experience body shaking at idle, it is recommended to visit a 4S shop to check the fuel supply pressure and intake pressure sensors. Abnormal fuel pump pressure or faulty readings from the intake pressure sensor can cause body shaking. The solution is to check the fuel pressure and replace components if necessary.
As a frequent driver, I've found that idle shaking in new cars is often caused by the engine not being properly broken in. When a car is fresh from the factory, its components are still in the adaptation period, and unstable air flow and fuel supply at idle can easily cause shaking. Loose ignition coils, improperly positioned spark plugs, or incorrect ignition timing can also cause vibrations. Poor fuel quality, such as containing impurities, can clog fuel injectors, leading to misfires and shaking. Unsecured engine mounts are also common, as there might be oversights during new car assembly. It's recommended to drive smoothly for the first few hundred kilometers, using steady speeds to help with the break-in process. If the shaking is severe, don't ignore it—visit a professional shop for a computer diagnosis of the ignition system. Regularly using high-quality gasoline and maintenance can prevent problems.
I've noticed that idle vibration in new cars is often related to electronic systems, such as the ECU receiving incorrect signals affecting fuel supply. Sensors like the throttle position or intake pressure probes may not be precise from the factory, causing signal distortion that makes the engine speed fluctuate. Short circuits or poor contact in high-voltage coils are also prone to manifest during idle. On new cars, wiring interfaces aren't yet firmly secured, and vibrations can loosen connections, leading to data errors. The solution is to have the dealership plug in an OBD scanner early to read fault codes—adjusting parameters or replacing components usually fixes it. Reducing frequent start-stop cycles while driving helps the system stabilize during the break-in period.
