What causes the ticking sound at idle that disappears when accelerating?
2 Answers
Ticking sound at idle that disappears when accelerating is typically caused by a faulty carbon canister purge valve, which should be replaced. The function of the carbon canister purge valve is to open the solenoid valve between the carbon canister and the intake manifold after the engine starts, allowing the adsorbed gasoline vapors in the carbon canister to enter the combustion chamber along with air for burning, thereby reducing emissions and fuel consumption. Below is relevant information about engine idling: 1. If the engine runs at idle for an extended period, the throttle opening will be very small, and the fuel injector will spray highly concentrated fuel to maintain engine operation. Therefore, idling itself is more likely to cause carbon buildup compared to driving or highway speeds. Prolonged idling will inevitably lead to more severe carbon buildup in the engine. 2. During engine idling, the temperature and pressure inside the cylinders are relatively low, prolonging the preparation time for fuel ignition. Additionally, the sealing performance of the cylinders decreases at this time, making it easier to produce knocking sounds and shortening the engine's service life.
I've been researching car abnormal noises, and the ticking sound at idle that disappears when accelerating is quite common. One of the reasons could be insufficient oil or wear in the hydraulic lifters. At idle, the oil pressure is low, preventing the lifters from working fully, creating gaps that cause ticking sounds; when accelerating, the increased oil pressure allows the lifters to function normally, and the noise disappears. Another possibility is a loose timing chain, which rattles at idle but tightens up at higher RPMs, making the noise go away. First, check the oil dipstick to see if the oil level is low or if the oil is dirty. If it's low, top it up, and if it's dirty, try changing to fresh oil. If the noise persists, it might be an issue with the lifters or the chain itself, requiring replacement or repair. Don't ignore this small problem, as it could indicate internal engine wear, and delaying repairs might lead to performance degradation or damage. Early detection and repair are key to maintaining vehicle health.
