Why does the car make a clunking sound when the accelerator is pressed too hard during startup?

[AshleyRose]

This type of sound is professionally referred to as "engine knocking." The main cause is the presence of carbon deposits on the top of the pistons. These carbon deposits form highly intense hot spots, which cause the fuel-air mixture in the combustion chamber to ignite prematurely before the intended ignition stroke. Factors that can trigger engine knocking include: 1. Excessive carbon buildup. 2. Overly advanced ignition timing. 3. Low engine RPM in a high gear. 4. Use of low-octane gasoline. Precautions for vehicle startup: 1. Before starting: When starting the car, do not turn the key immediately after inserting it. This can cause unnecessary stress on the battery and starter motor, as the vehicle needs time to prepare. Immediate startup can negatively affect the vehicle's ignition system. 2. During startup: For vehicles with push-button start, do not press the brake pedal initially. Press the start button once to simulate turning the key to the ON position, wait a few seconds, then press the brake pedal and start button to ignite the engine.