What Causes Car Idle Shaking?

2 Answers
Gavin
07/29/25 1:18am
Car idle shaking can be attributed to the following reasons: 1. Unstable oil pressure: Abnormal fuel pump supply pressure or malfunctioning intake pressure sensor values can cause body shaking; 2. Severe engine carbon buildup: Dirty throttle body or excessive carbon deposits in fuel injectors; 3. Ignition system issues: Poor ignition system performance or suboptimal spark plug firing conditions can also lead to such faults; 4. Aging engine components: Engine mounts are responsible for absorbing minor vibrations during operation. If the engine mounts fail, these vibrations will transmit to the steering wheel and cabin, causing shaking during idle.
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McRonan
08/12/25 5:27am
When encountering engine idle shaking, I know it's mostly an engine issue. Common causes of idle shaking include severe carbon buildup blocking the intake or fuel injectors, leading to uneven combustion of the air-fuel mixture; aging spark plugs or damaged ignition coils resulting in insufficient spark energy; a stuck idle control valve or vacuum hose leaks causing unstable air flow. It could also be due to aging and loose engine mounts with poor damping effect. I've experienced shaking while driving and often check it myself: first by replacing spark plugs and cleaning the throttle body. If it still shakes, professional testing of sensors or the ECU is needed. Regular maintenance is key; adding fuel system cleaner monthly can effectively reduce carbon buildup and prevent idle abnormalities. If left untreated for a long time, worsening shaking can affect driving safety, accelerate part wear, and increase fuel consumption.
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