What Causes Intermittent Shaking When Idling in Park?
3 Answers
Intermittent shaking when idling in park can be caused by: 1. Unstable oil pressure. If you've already cleaned the engine carbon deposits, throttle body, replaced oil pads and spark plugs, but the vehicle still shakes at idle, it's recommended to visit a 4S shop to check the fuel supply pressure and intake pressure sensor; 2. Aging engine components. Worn engine mounts may cause vehicle shaking. If these parts fail, the vibrations will transmit to the steering wheel and cabin; 3. Excessive dirt in the engine or carbon buildup in fuel injectors. When carbon deposits are excessive, gasoline sprayed by cold-start injectors gets largely absorbed by carbon deposits. After starting, the gasoline adsorbed on carbon deposits gets sucked into the cylinders by engine vacuum for combustion, enriching the air-fuel mixture. This results in fluctuating lean/rich combustible mixtures, causing shaking.
With years of experience in car repair, I've noticed that intermittent shaking while idling is quite common, usually caused by severe carbon buildup on the spark plugs leading to inconsistent ignition, making the engine run unevenly. After several years of use, spark plug electrode erosion or excessive gap can cause intermittent sparking, resulting in vibrations. A clogged air filter restricting the air intake and disrupting the air-fuel mixture ratio is another culprit, causing idle speed to fluctuate. If the fuel injectors are clogged, uneven fuel supply can lead to intermittent shaking—don't ignore this. Worn-out engine mount cushions reduce damping, making the shaking more noticeable as it transfers to the car body. Sometimes, carbon buildup on the throttle body can jam the idle control valve, adding to the problem. I recommend visiting a professional shop early to diagnose trouble codes with an OBD scanner and try replacing spark plugs and the air filter. Don't delay until it becomes a major issue like high fuel consumption or engine damage. Regular check-ups and maintenance every 20,000 kilometers can prevent such problems.
As a novice driver with just one year of experience, I was startled when my car started shaking intermittently while parked. After researching online, I found that spark plug issues are often the cause, with carbon deposits leading to unstable ignition. Clogged fuel injectors or a dirty air filter can also cause abnormal idle vibrations. I even heard that aging engine mount rubber affects shock absorption. I opened the hood and touched the engine—the shaking transmitted to the seat was truly uncomfortable, so I rushed to the 4S shop for diagnosis. The technician said minor issues like these could become more expensive if ignored, such as damaged spark plugs affecting the ignition coil. Now I’ve learned to regularly maintain spark plugs and air filters to reduce risks—safety first, especially since shaking on highways during rain is even more dangerous. Don’t skimp on a few hundred bucks now only to pay big repair costs later.
