Why is the idle speed high during cold start?

[VonHaley]

Cars have high idle speed during cold start for the following reasons: 1. High idle speed during startup is normal: (1) The car needs high speed to make the engine reach normal working conditions as soon as possible, requiring a richer mixture, so the intake air volume and fuel injection volume will increase, resulting in higher speed. (2) Increased oil viscosity during cold start: During cold start, the idle stepper motor automatically adjusts to increase the intake air volume, allowing more air to enter the cylinder, so high idle speed is normal. 2. Excessive carbon deposits: Timely cleaning of the throttle and idle motor can generally solve this problem.

[ReeseMarie]

I've been driving for over a decade, and high idle speed during cold starts is very common. When the engine is cold, it needs to increase RPM to warm up quickly so the catalytic converter can work effectively. The idle speed usually drops after a few minutes. However, if the idle speed remains above 2000 RPM for an extended period or is accompanied by shaking, it could indicate a faulty coolant temperature sensor, a vacuum leak, or a dirty throttle body. I've seen many car owners ignore such minor issues, only to face skyrocketing fuel consumption or even engine stalling later. That's why I recommend having a technician scan for trouble codes during every maintenance check to address problems early. While it's normal and nothing to worry about, persistent abnormalities should be taken seriously to avoid breakdowns on the road.

[MacLydia]

My experience in car repair tells me that high idle speed during cold starts is the result of engine automatic adjustment. When the temperature is low, the system increases air intake and fuel supply to maintain stable operation, which is reasonable. However, abnormally high idle speed is different, such as exceeding the normal range, and the reasons include a damaged air flow meter or aging wiring. I've found that many minor issues can accumulate and lead to major problems, so I recommend self-observation: listen to the engine sound and watch the tachometer changes after starting; if the idle speed is unstable, use diagnostic tools promptly to check. This can save you from spending a lot on repairs and also protect the car's lifespan.

[SanEleanor]

I find that a slightly higher idle speed during cold starts is no big deal. The car adjusts itself to balance, and it drops down once it warms up. Unless the idle remains consistently high and the car shakes when driving, then it might be a sensor malfunction or excessive carbon buildup. Remember to get it checked at the shop promptly to ensure safety.