What is the reason for diesel engine idling vibration but no vibration when accelerating?
3 Answers
Diesel engine idling vibration but no vibration when accelerating is caused by: the engine's idle excitation frequency couples with the natural frequency of the steering system or vehicle body, generating idle resonance which leads to vibration. When accelerating, the engine's excitation frequency changes and increases, avoiding the natural frequency points of the transmission system or certain vehicle body components, thus eliminating the vibration. It is quite normal for an engine to have slight vibration during idling, as all engines exhibit this phenomenon. Under normal circumstances, it does not affect the driving and riding experience of vehicle owners, and no treatment is required. Only when the engine's idling vibration is excessive can it be considered a fault.
I've been driving diesel cars for ten years and often encounter the issue of idle shaking that disappears when accelerating. This is usually caused by carbon buildup in the fuel injectors or a clogged EGR valve. At idle, the engine runs at low RPM with minimal and uneven fuel injection - even minor contamination can make the engine shake like a tractor. When accelerating, the increased RPM ensures sufficient fuel supply and stable combustion, naturally eliminating the vibration. Other common causes include aged engine mounts or damaged rubber cushions, where vibrations are noticeable at low speeds but not at high speeds. I once worked on a vehicle where a stuck EGR valve caused unstable exhaust gas recirculation, leading to incomplete combustion at idle. I recommend first inspecting the fuel injection system, cleaning the injectors and EGR valve, then checking the condition of the mounts. Don't underestimate this shaking - prolonged vibration can damage engine components like valves or piston rings. Regularly using high-quality diesel additives can help prevent carbon buildup.
Buddy, my diesel car has been acting up lately too, shaking like crazy at idle but smoothing out when I step on the gas. From what I've learned, the main culprits are usually dirty injectors or clogged with debris – at idle the fuel spray is minimal causing unstable combustion and shaking, while higher flow rates when accelerating mask the issue. It could also be an EGR system malfunction where the idle opening/closing isn't working right, causing major exhaust fluctuations. Sometimes it's worn engine mounts making vibrations more noticeable at low speeds, but the stronger power at higher revs suppresses them. Modern diesels have tons of sensors – a faulty mass airflow sensor can also trigger rough idling. My advice? Get it to a pro shop for a diagnostic scan, focusing on injector data and EGR status. Don't put it off – breaking down on the road would be a nightmare. Toss in some cleaner for regular maintenance too.
