What Causes Diesel Engine Idle Vibration When Cold?
2 Answers
Reasons for diesel engine idle vibration when cold: 1. Poor combustion in the cylinder; 2. Insufficient engine temperature; 3. Large spark plug gap; 4. Aging or leaking high-voltage wires of spark plugs; 5. Aging ignition coils; 6. Dirty air flow meter; 7. Poor fuel quality. A diesel engine is an engine that burns diesel fuel to release energy. Diesel engines are divided into: 1. Spark-ignition engines: Gasoline engines inject gasoline into the intake pipe to mix with air and form a combustible mixture, which then enters the cylinder and is ignited by the spark plug to expand and perform work; 2. Compression-ignition engines: Diesel engines directly inject diesel into the engine cylinder through the fuel injection pump and nozzle, where it mixes uniformly with the compressed air in the cylinder and spontaneously ignites under high temperature and pressure, pushing the piston to perform work.
I've been driving a diesel car for the past few years, and rough idling during cold starts in winter is really common. The main reason is that diesel viscosity is high when the engine is cold, leading to poor atomization and uneven combustion in the engine. Fuel system issues play a big role—carbon buildup in the injectors or unstable fuel pressure can cause misfires in individual cylinders. On the intake side, a dirty throttle body or clogged air filter reduces air intake. Fuel quality also matters—using low-grade diesel can lead to carbon deposits, worsening the roughness. Worn engine mounts or deteriorated rubber bushings can also transmit vibrations. I must remind everyone that regular maintenance is crucial—for example, cleaning the injectors every 20,000 km, changing the oil, and using appropriate diesel additives in winter can significantly improve performance. Don’t ignore small issues—prolonged rough idling can damage engine components.
