What is the normal idle speed for an automatic car?
2 Answers
When starting a cold engine, the idle speed is typically around 1200~1500 RPM. Once the engine reaches normal operating temperature, the idle speed usually stabilizes at 800~900 RPM. If the car is in Drive (D) gear without pressing the accelerator pedal, the speed will be approximately 5-10 km/h. Relevant information about idle speed is as follows: 1. Definition: Idle speed refers to an operating condition of the car where the engine runs without being engaged in any gear. The engine speed during idle is called idle speed. Idle speed can be adjusted by modifying the throttle opening size, among other methods. Essentially, idle means the engine is 'producing power without doing work.' 2. Driving idle: When the car is in gear without pressing the accelerator pedal or when the accelerator pedal is released during driving, maintaining the minimum throttle opening, the engine speed matches the parking idle speed. This condition is referred to as driving idle.
I've been driving for over a decade, and automatic cars usually idle around 800 RPM, which is quite normal. There might be slight variations between different vehicles. For instance, my old car would reach over 1000 RPM during cold starts, dropping to around 800 in summer, and stabilizing once the engine warmed up. If the idle speed is too high, say exceeding 1000 RPM, it not only wastes fuel but also harms the engine—time to check if the air filter is dirty. An unstable idle can cause the car to shake, so don't ignore it; try turning off the engine at red lights in traffic to save fuel. Automatic transmission idle speed is significantly affected by the AC—turning it on might increase RPM by about 100, boosting fuel consumption. Make it a habit to check the dashboard after starting; keeping RPM between 600 and 1000 is safe and efficient, ensuring engine health and prolonging your car's lifespan.
