What Causes Idle Shaking When the Car Gets Hot?
2 Answers
Reasons for idle shaking when the car is hot include severe engine carbon buildup; ignition system issues; unstable oil pressure. Severe Engine Carbon Buildup: The most common cause of car shaking is a dirty throttle or excessive carbon buildup in the fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold-start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start. Ignition System Issues: Check the working condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance of the ignition system or inadequate spark plug firing can also lead to such faults. Unstable Oil Pressure: If you have already cleaned the engine carbon buildup, cleaned the throttle, replaced the oil gasket and spark plugs, but still notice body shaking at idle, it is recommended to visit a 4S shop to check whether the fuel supply pressure and intake pressure sensor are functioning properly. Abnormal fuel pump supply pressure or incorrect readings and poor performance of the intake pressure sensor can all cause body shaking.
I often encounter this issue with my old car – when the engine gets hot, the idle shakes annoyingly, like the engine is doing a swing dance. The main reasons could be: aging spark plugs or failing ignition coils causing unstable ignition due to increased gaps under high temperatures; excessive carbon buildup in the throttle body, which hardens when hot and blocks airflow, disrupting the air-fuel mixture; or insufficient fuel pump pressure, leading to inadequate fuel delivery, with clogged fuel injectors adding to the trouble. If the engine mounts are worn or the rubber has hardened, thermal expansion can make vibrations more noticeable. From a safety perspective, don’t underestimate the shaking – significant steering wheel vibrations can affect control, especially in traffic jams where the wobbling can make you dizzy. After parking, it’s advisable to inspect the engine bay visually for loose wiring or mounts. If unsure, consult a professional mechanic promptly. Regular throttle body cleaning and spark plug replacements can prevent many of these issues.
