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Why does the car suddenly shake when idling?

1 Answers

Oliveira

07/29/25 4:09pm

Car idling shaking is caused by severe engine carbon deposits, ignition system failure, unstable oil pressure, and aging engine components. Severe engine carbon deposits, excessively dirty throttle, or excessive carbon deposits in the fuel injector are the most common causes of engine shaking. Here is a detailed explanation: 1. After a car has been driven for a period of time, a dirty throttle can cause the throttle to not close tightly or the idle stepper motor to get stuck, both of which can result in excessively high engine idle speed. Carbon deposits generated during engine operation can also cause vehicle shaking, especially when starting the vehicle. The engine may shake more than usual, and sometimes it may even fail to start on the first attempt. 2. Ignition system failure: Spark plugs, high-voltage wires, and ignition coils may experience poor ignition system performance after working for a certain period. 3. Unstable oil pressure: Abnormal fuel pump supply pressure or incorrect and poor performance of the intake pressure sensor can cause engine shaking. 4. Aging engine components: Turning on the electrical system when the car engine is idling will increase the engine load, causing the idle speed to drop. To compensate for the shaking caused by the drop in idle speed, the engine will automatically increase the speed slightly. If the shaking during idling does not decrease when the car's air conditioning compressor is running, it may be due to aging engine mounts, which need to be replaced promptly.

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