What Causes Severe Shaking When the Car is Running?
3 Answers
The reasons for severe shaking when the car is running are: 1. Worn engine mounts; 2. Unstable oil pressure, abnormal fuel pump supply pressure, or faulty intake pressure sensor readings; 3. Severe engine carbon buildup, where gasoline injected by the cold start injector is largely absorbed by carbon deposits, resulting in an overly lean air-fuel mixture during cold starts; 4. Ignition system issues, such as faulty spark plugs or ignition components; 5. Uneven tire pressure, causing uneven force distribution while driving. Solutions for severe shaking when the car is running include: 1. Check oil pressure and replace faulty components; 2. Inspect or replace spark plugs; 3. Promptly replace brake discs; 4. Clean the fuel system, check the idle control valve for carbon buildup, inspect oil pressure, and replace faulty parts; 5. Inspect the engine to identify problematic components; 6. Clean the fuel filter.
Last time my old Jetta started shaking like crazy when I hit 80 km/h, so I rushed to the repair shop for a lift inspection. The veteran mechanic said it was most likely a wheel balancing issue - the front wheel balancing weights had fallen off, causing uneven centrifugal force during high-speed rotation. Chassis problems can also cause shaking, like when the lower control arm bushings age and crack, throwing off wheel alignment, or when the CV joint wears severely, even producing clicking sounds. Then there's the dreaded warped brake disc situation - sudden braking at high temperatures followed by water contact can create wavy deformations on the disc, making the whole car dance with light brake pressure. Remember there are two types of shaking: low-speed shaking points to engine mounts or spark plugs, while high-speed shaking means checking tires and drivetrain first. Don't delay - get it inspected ASAP.
Last week, I had this awful experience while driving my kid to school. The whole car was shaking at speeds over 40 mph, even the milk tea in the passenger seat was wobbling. The mechanic first had me check the tire pressure, and sure enough, the front right tire was down to just 1.8 bar. He said a difference of more than 0.3 bar in tire pressure between the four wheels can cause body resonance, especially with front wheel pressure differences being more sensitive. He also reminded me to check the tire wear, and we found severe inner wear on the left rear tire, with the tread almost gone on the inside. Even scarier was when we lifted the car and found three cracks in the engine mount rubber pads—if these fail, even gear shifts can become jerky. His advice was to first recall if you've recently hit any curbs when experiencing vibrations, as tire deformation and wheel rim warping are among the most common causes.
