What Causes Abnormal Noises When Driving at High Speed?

[VanGenevieve]

Abnormal noises when driving at high speed can be caused by the following reasons: 1. Valve noise: The engine makes abnormal noises after starting, which is the sound of the valves, especially right after starting. This occurs because the oil pressure hasn't built up yet, and the valves aren't properly lubricated. The situation will improve after a short while. 2. Engine "backfire" issue: Abnormal noises when decelerating or lifting off the throttle may indicate an engine "backfire" issue, commonly referred to as engine "popping." Excessive carbon buildup on the valves or incorrect valve timing can cause such noises. 3. Prolonged oil usage without replacement: If there is no specific pattern to the noise, but the engine sound noticeably increases, it is highly likely due to dirty or degraded oil. After replacing the oil, you can clearly feel a reduction in engine noise.