What Causes Car Shaking at Low Speed?
2 Answers
Reasons for car shaking at low speed are as follows: Dirty throttle body or excessive carbon deposits on fuel injectors: After the car starts, gasoline adsorbed on the carbon deposits will be sucked into the cylinder by the engine's vacuum suction for combustion, enriching the air-fuel mixture. The combustible mixture in the engine becomes alternately lean and rich, causing idle shaking after a cold start. Solution: Clean the fuel system and check if the idle speed motor has carbon deposits that need cleaning. Ignition system issues: Check the working condition of spark plugs, high-voltage wires, and ignition coils. Poor performance of the ignition system or improper spark plug firing can also lead to such faults. Unstable fuel pressure: It is recommended to visit a 4S shop to check whether the fuel supply pressure and intake pressure sensor are normal. Abnormal fuel pump supply pressure or incorrect values and poor performance of the intake pressure sensor can cause body shaking.
Last year, my old car shook violently when stuck in city traffic, especially noticeable at low speeds under 20 km/h. I suspect it might be related to carbon buildup, particularly in the throttle body and fuel injectors. Excessive deposits can block air intake, disrupting the air-fuel ratio and making the engine struggle to breathe. It could also be due to an aging ignition system, where delayed spark plug replacement leads to insufficient ignition energy, causing misfires. Suspension and tires are also potential culprits—low tire pressure or deformed rims can make the body wobble unsteadily. I checked some resources and found that clutch wear in automatic transmissions or improper throttle coordination in manual transmissions can also induce shaking. Don’t underestimate this issue—letting it persist can damage engine components or increase fuel consumption. A timely visit to the repair shop for carbon cleaning or wheel balancing can solve most of the problem, costing little while saving hassle.
