What is the appropriate idle speed for an automatic transmission?

[Corbin]

An idle speed of 500 to 850 RPM is appropriate for an automatic transmission, while the instantaneous idle speed during a cold start is around 1500 to 2000 RPM per minute. The characteristics of an automatic transmission car are: 1. Easy to operate, simple to learn, and easy to master driving techniques; 2. High driving comfort with relatively smooth gear shifting; 3. High safety factor, reducing driver fatigue. The gears of an automatic transmission car include: 1. P gear is the parking gear, used for long-term parking of the vehicle; 2. R gear is the reverse gear, engaged when the vehicle needs to move backward; 3. N gear is the neutral gear, engaged when the vehicle is parked for a short time without turning off the engine; 4. S gear is the sport mode, making the vehicle drive more sporty; 5. M gear refers to the manual mode, where the driver manually completes the gear shifting when the gear lever is engaged in M gear.

[MasonLynn]

For automatic transmission vehicles, maintaining an idle speed between 700 and 800 RPM when parked is generally ideal. This range ensures smooth engine operation and prevents shaking or stalling. If the idle speed is too low, such as below 600 RPM, the engine may become unstable; if it's too high, exceeding 1000 RPM, fuel consumption will increase. I've driven many automatic cars, and especially during cold starts, the idle speed tends to be higher initially, around 900 to 1000 RPM, then returns to normal once the engine warms up. During regular driving, if the air conditioning is on or there's a heavy electrical load, the idle speed may rise slightly, which is normal. However, if the idle speed frequently fluctuates or becomes unstable, it could indicate a dirty throttle body or a faulty sensor. I recommend getting it checked promptly to avoid bigger issues that could affect driving comfort. Keeping an eye on the tachometer on the dashboard and making it a habit can help save fuel and extend your car's lifespan.

[SanAriel]

Idle speed is quite crucial for automatic transmission vehicles, with a normal range typically between 650 to 850 RPM. From my experience, it's normal for the engine to idle slightly higher when first started, around 800 to 900 RPM, which quickly drops as the engine warms up. Too low idle speed can cause the car to shake and stall easily, while excessively high idle wastes fuel and may indicate issues with the mass airflow sensor or idle control valve. Before driving, check the tachometer—a steady needle around 700 RPM is ideal. If you notice abnormalities, such as unusually high or low idle when the engine is cold, visit a repair shop promptly as it could be due to carbon buildup or wiring issues. Regular maintenance like throttle body cleaning helps maintain stable idle speed, reduces the chance of malfunctions, and ensures smoother driving.

[DelMorgan]

An automatic transmission idling at around 700 RPM is considered normal. Temperature has a significant impact: during cold starts, it may be higher, around 900 RPM, and will drop to 650-800 once the engine reaches normal operating temperature. If the idle speed is too low, the engine may shake; if it's too high, it will consume more fuel. Check the dashboard—if the idle is unstable, it could be due to carbon buildup or a faulty sensor. Address the issue promptly to avoid further problems.

[Carson]

The normal idle speed for an automatic transmission car is between 600 to 800 RPM, with a reasonable fluctuation range. After starting, the engine may run slightly higher before warming up, then it will stabilize—don't worry about these minor fluctuations. However, if the idle speed is consistently abnormally high, such as reaching 1000 RPM, or as low as 500 RPM, it's necessary to investigate the cause, which could be a clogged intake pipe or aging spark plugs. Simply put, this isn't a major issue—just a detail of daily car use to ensure smooth driving.

[Ariel]

Idle speed issues are quite common in automatic transmission vehicles, with the ideal range being between 700 to 800 RPM. From my experience with different models, gasoline vehicles generally run slightly lower while diesel vehicles tend to be higher, with variations between new and old vehicles. Influencing factors include ambient temperature and AC usage: in summer when the AC is on, the idle might occasionally rise to 850 RPM; during cold starts in winter, it may run slightly higher. If the idle speed consistently fluctuates below 600 RPM or exceeds 900 RPM, it indicates maintenance is needed - simply check the throttle body or oxygen sensor. Maintaining proper idle speed helps with fuel efficiency and engine longevity.