Why does the idle speed suddenly increase?
2 Answers
It is due to a faulty throttle in the vehicle. Hazards of high idle speed: High idle speed leads to increased fuel consumption. When the engine is cold, it can cause mechanical wear inside the vehicle and is not conducive to oil lubrication. A damaged sensor can cause unstable idle speed, difficulty in cold starts, and in severe cases, may even result in no idle speed, causing the engine to stall when the accelerator is released. Normal idle speed: Generally, normal idle speed ranges between 700-1500 rpm, slightly higher when the engine is cold. Both excessively high and low idle speeds are detrimental to engine operation. Low idle speed prolongs warm-up time and reduces starting power, while high idle speed increases fuel consumption, promotes carbon buildup, and accelerates engine wear.
I often encounter car owners asking this question - sudden idle speed increase is quite common. In most cases, it's due to a faulty idle control valve in the engine. When this component gets stuck or accumulates too much carbon deposit, the engine automatically increases RPM to compensate. Alternatively, there might be a vacuum leak in the intake pipe, such as a cracked hose or loose connection, allowing air to leak in and disrupt the air-fuel mixture ratio. Sometimes, issues with fuel injectors in the fuel system causing excessive fuel injection can also make the RPM surge. For daily drivers, I suggest first checking the engine compartment yourself for obvious air leakage sounds or unusual odors, and gently shaking the intake pipes to test. However, if this situation occurs, don't delay too long - high RPMs may cause engine overheating or increased fuel consumption. It's advisable to take it to a repair shop for professional diagnosis with specialized equipment, as this issue can escalate into bigger problems. Safety first - if the idle is unstable when parked, avoid driving at high speeds as it could lead to accidents.
