What is the normal idle speed for an automatic transmission car?
3 Answers
Under normal conditions, the idle speed for an automatic transmission car is 700-800 RPM. Below are the specific details about car idle speed: 1. High idle speed: The hazards of high idle speed include increased fuel consumption, higher engine operating temperatures, and increased mechanical wear. 2. Low idle speed: The hazards of low idle speed are that the car is prone to stalling when starting, and frequent starts can damage the engine and starter. Additionally, excessively low idle speed may cause the vehicle to stall while driving, and over time, carbon deposits can accumulate inside the engine cylinders, leading to sluggish acceleration. 3. Prerequisites for adjusting idle speed: The engine temperature should be normal, valve clearance should be appropriate, the ignition system should be functioning properly, all pipelines should be well-sealed, the choke should be fully open, and the throttle should be able to close tightly.
As a long-time automatic transmission car owner, my experience tells me that the normal idle speed typically ranges between 650 to 850 RPM, depending on the vehicle condition and ambient temperature. For instance, during winter startups, it might be slightly higher, reaching around 900 RPM, to allow the engine to warm up quickly; in summer, it may drop to approximately 700 RPM. Stable idle speed is crucial as it reflects whether the engine is running smoothly. Too high an idle increases fuel consumption and accelerates component wear, while too low can lead to stalling. Additionally, when stuck in traffic at a red light, significant fluctuations in the tachometer might indicate that the air filter or spark plugs need checking. Regular maintenance ensures the idle speed stays within the ideal range, prolonging the vehicle's lifespan.
Based on my knowledge of automotive maintenance, the normal idle speed for automatic transmission vehicles typically ranges between 600 and 900 RPM, specifically regulated by the engine model and ECU control module. During a cold start, the RPM is higher and drops to a stable level after a few minutes, with around 750 RPM being quite common. Factors affecting idle speed include altitude, whether the air conditioning is on, or the battery load size; in high-altitude areas, the idle speed may be slightly lower to conserve oxygen. Maintaining a normal idle speed can improve fuel efficiency and reduce exhaust emissions. When checking the idle speed, ensure the dashboard reading is steady without fluctuations, which is a sign of a healthy engine. If it remains consistently high for an extended period, consider cleaning the throttle or adjusting the sensors.
