What are the reasons for the abnormal noise in the idling of the Corolla 1.2T engine?

[MacKylie]

Corolla 1.2T engine idling abnormal noise reasons are as follows: Timing chain elongation and wear: Timing chain elongation is generally caused by metal fatigue. After prolonged driving, combined with the high-temperature working environment of the timing chain, it is easy to produce chain elongation, resulting in abnormal noise. Camshaft and crankshaft wear: If the vehicle is filled with inferior engine oil, excessive sludge can be generated in the engine, blocking the lubrication oil passage and preventing the oil from reaching the components that need lubrication and cooling. This can cause wear on the camshaft, crankshaft, and connecting rod bearings, leading to abnormal noise. Increased clearance in the variable timing wheel: Variable valve timing can be adjusted according to the engine speed and operating conditions, usually by using hydraulic pressure to control the internal rotor of the camshaft timing gear to achieve a certain degree of advance or delay. If the internal rotor of the variable timing wheel is stuck or the oil chamber is worn, it can lead to increased clearance and abnormal noise.