What is the ideal idle speed for a car?
2 Answers
Normally it ranges between 700-800 RPM. Below is relevant information about car idle speed: 1. The function of car idle speed: Idle speed is an operational state of a car, referring to the engine running in neutral gear. The engine speed during idle is called idle speed. Idle speed can be adjusted by modifying parameters like throttle opening. Idling means the engine is "producing power without doing work". When the engine is running and the accelerator pedal is fully released, the engine enters idle state. 2. Causes of unstable idle speed: Direct causes refer to mechanical components being dirty, worn, or improperly installed, leading to variations in cylinder power output which creates imbalance among cylinders, resulting in unstable idle speed; Indirect causes refer to abnormalities in the engine's electronic control system causing poor combustion mixture, making it difficult to balance cylinder power output and resulting in unstable idle speed.
As an auto repair technician, I believe idle speed issues need to be analyzed based on specific vehicle models. For mainstream cars nowadays, the normal idle speed after warming up usually fluctuates between 700-900 RPM - as long as the needle stays steady, it's fine. It's completely normal for the RPM to spike up to 1200 during cold starts since the ECU is heating up the catalytic converter. Don't panic if the RPM temporarily jumps to around 1000 when the AC is on or during full steering lock. If you notice the tachometer shaking like a vibrating phone or fluctuating like a seesaw at stoplights, it's likely caused by carbon buildup in the throttle body that needs cleaning. Remember not to rev the engine aggressively right after ignition - it's really bad for the car.
