What is the normal idle speed of a car?
2 Answers
Generally, the idle speed of a car ranges from 700 to 900 RPM (revolutions per minute). When the air conditioning is turned on, the idle speed increases to 800-850 RPM. It's important to note that not all vehicles have the same preset engine speed during idle conditions. Idle speed refers to the state where the engine runs naturally without pressing the accelerator after starting the car, and the RPM at this time is called the idle speed. It's crucial to check the idle speed when the engine is at operating temperature, meaning when the coolant has reached its normal temperature, as idle speed can vary with coolant temperature. When the coolant temperature is very low, the engine will automatically increase the idle speed to help the car warm up faster, allowing it to reach the optimal operating temperature more quickly, reducing wear and improving performance.
Oh, I often think about this issue. My old car idles steadily at around 750 RPM, but when starting cold, it can rev up to over 1000 RPM, then drops as it warms up. Modern cars generally fluctuate between 700 and 850 RPM, with newer models being even lower to save fuel. I’ve also noticed significant differences between brands—Japanese cars tend to idle lower, while German cars run slightly higher. Temperature plays a big role; cold starts in winter see higher RPMs due to thick engine oil, while in summer, the AC load may slightly increase idle speed to prevent stalling. Engine type matters too—gasoline engines usually idle between 600 and 800 RPM, while diesel engines, thanks to their torque, can go as low as 500 RPM. Occasional idle instability might indicate a dirty throttle body or sensor issues, so timely checks are crucial to avoid stalling and engine damage. Overall, proper idle speed keeps your car reliable and cost-effective.
