Why does the car have high idle speed when cold?
3 Answers
Cold start high idle speed is caused by the following reasons: 1. If the weather is extremely cold, the idle speed after starting will be below 1,000 rpm, approximately 900 rpm, to protect the engine. 2. If the temperature is above 15 degrees Celsius when starting the vehicle, the idle speed after starting will be around 1,200 rpm, to allow the engine oil to quickly warm up and lubricate the components. Solutions are as follows: 1. Clean the throttle body and perform matching; 2. Check for missing or leaking exhaust pipes; 3. Inspect the intake tract for carbon buildup; 4. Check the coolant temperature sensor.
That morning when I started the car, the engine RPM surged to around 2000, which initially worried me. Actually, it's normal for a car to idle at higher RPM when cold - the computer system intentionally increases the speed to help the engine warm up faster and protect components. However, if the RPM remains excessively high for too long (say over five minutes), it might indicate a stuck idle control valve or faulty temperature sensor, especially common in winter. When I encountered this before, I noticed about 10% higher fuel consumption, more noticeable during cold winter starts. I recommend regularly checking if the air filter is dirty or if the idle control valve is sticking. Lightly pressing the brake pedal a few times or letting the engine warm up for several minutes should bring the RPM down. Remember not to rev the engine aggressively as it may cause damage. If the issue persists, get it checked at a garage without delay.
Having driven for decades, it's quite common for the engine to rev higher during a cold start, just like warming up before a run. When the car is cold, the computer automatically increases the idle speed to accelerate catalyst warm-up, typically around 1200-1500 RPM. However, if you notice the RPM exceeding 1800 and staying high for a prolonged period, it's time to be cautious. This could indicate issues like a vacuum leak or idle control valve malfunction, which may lead to black smoke or engine shaking. I've dealt with this a few times myself—simple checks include inspecting the engine cover seal and ensuring wiring connectors aren’t loose. Regular maintenance, such as cleaning throttle body deposits, can prevent this. Don’t panic, but don’t ignore it either, as it may cause excessive fuel consumption or emissions violations, especially in older models. Addressing it promptly saves money and hassle.
