What are the reasons for high engine speed and abnormal noise during cold start?
2 Answers
Cold start with high engine speed and abnormal noise is caused by: dirty engine oil, excessive viscosity, and piston knocking. The reasons for high engine speed are: 1. Sudden increase in throttle opening; 2. Fuel injector dripping or clogging; 3. Slipping or damaged air conditioning clutch; 4. Air intake system leakage; 5. Insufficient engine output power. The solutions for high engine speed are: 1. Adjust the throttle opening; 2. Replace the fuel injector, air conditioning clutch, air intake system, and engine. The function of the engine is: to convert the thermal energy of gasoline into mechanical energy by burning and expanding gas in a sealed cylinder, thereby pushing the piston to perform work.
As an average car owner who frequently drives in cold weather, I've noticed that high engine RPM accompanied by rattling or gurgling noises during cold starts is actually quite common. Often, it's due to oil-related issues. The cold weather makes the oil too thick, so when starting the car, it's like a person stretching after waking up—the engine spins rapidly but with noticeable hesitation, causing friction between components and generating noise. Additionally, old or degraded oil, or using low-quality oil with incorrect viscosity, can exacerbate the problem. Poor fuel injection, such as from dirty injectors spraying inaccurately during cold starts, can also lead to RPM surges and harsh sounds. Sometimes, this is related to clogged air filters or minor internal engine wear, like insufficient lubrication of valve stems. I must emphasize that ignoring these noises could lead to engine damage, such as scoring the cylinder walls, which would be a costly repair. If this occurs, I recommend first changing the oil and cleaning the fuel system. Warming up the car for a few minutes can also help reduce these issues. Of course, if the problem persists, it's best to have a trusted mechanic inspect specific components.
