What Causes Engine Shaking?

[JakeFitz]

Engine shaking can be caused by: 1. Aging or loosening of engine mounts; 2. One or more cylinders not functioning properly; 3. Carbon buildup in the engine, including on the throttle valve, cylinders, and spark plugs; 4. Fuel system malfunctions; 5. Intake system issues; 6. Normal reaction during cold starts. Solutions include: 1. Cleaning the throttle valve; 2. Replacing a set of spark plugs; 3. Seeking professional repair services. An engine is a machine that converts other forms of energy into mechanical energy, including internal combustion engines, external combustion engines, jet engines, electric motors, etc.

[DerekLee]

I remember last year when I was waiting at a red light in my old Passat, the steering wheel was shaking like a phone vibration. Later, the mechanic told me that this was most likely due to worn engine mounts—when the rubber in the engine suspension cracks, it can’t absorb the vibrations. Worn spark plugs causing unstable ignition are also common, especially during cold starts when the shaking gets worse. Replacing the spark plugs made a big difference. Carbon buildup in the throttle body is particularly annoying—it feels like the engine is gasping for air, jerking unevenly. Last time, cleaning the throttle body cost me over 200 yuan, but the idle stabilized immediately afterward. If the shaking worsens when accelerating, it’s probably time to clean the fuel injectors. The scariest is misfire-induced shaking—it feels like a horse limping on one leg, jerking violently. In that case, never push through; pull over immediately and call for roadside assistance.

[Rhett]

My Corolla with 80,000 kilometers on it was shaking badly last month. After checking for a long time, I found out it was a burnt ignition coil. The mechanic said the four ignition coils are like quadruplets - if one fails, the other cylinders get messed up too. A clogged air filter can also cause shaking. Last time I drove through a sandstorm for two days, the filter was caked like a pancake. After replacing it, the engine breathed smoothly again. Once I mistakenly filled up with 92-octane gas and it shook like having a seizure. The technician said the knock sensor was protesting. Now I've learned my lesson - if the fuel cap says 95, I never compromise. Older cars are especially afraid of vacuum hose leaks. Last year a small crack in the rubber hose made the idle shake so much it spilled water from my cup. I bought a set of vacuum hoses myself for just 80 yuan, much cheaper than the dealership quote.

[LeMalia]

The engine shakes like a person with malaria, most commonly due to three root causes. Insufficient blood supply to the heart—the fuel pump pressure is unstable or the fuel line is clogged, causing uneven fuel injection and resulting in pronounced shaking. Breathing difficulties—an air leak in the intake system or a dirty air filter disrupts the air-fuel mixture concentration. Nervous breakdown—the ignition coil is particularly finicky and will stop working if the voltage is unstable. There are also skeletal issues like aging engine mounts, where rubber components harden like stone in three to five years. The most troublesome is carbon deposit-induced shaking; carbon buildup on the piston crown acts like a troublemaker, intermittently altering the compression ratio. Last time, an endoscope revealed carbon deposits in the cylinder that had formed scabs, and it only settled down after walnut shell blasting.