What Are the Symptoms of Engine Knocking?
2 Answers
Engine knocking manifests as follows: Knocking typically presents as a rhythmic, continuous abnormal sound from the engine while driving, resembling the sound of lightly tapping a triangle. If the throttle is fully open in a high gear or when climbing a hill, the sound becomes louder. The engine also noticeably loses power. Therefore, the severity of knocking can be gauged by the loudness of the sound. Below is relevant information: 1. The quickest and most effective method to suppress knocking is to retard the ignition timing, thereby reducing combustion pressure. 2. The principle of operation of a knock sensor is that when engine knocking is detected, the ignition timing is retarded to a point where knocking does not occur. Once the engine stops knocking, the ignition timing is gradually restored. The knock sensor uses an accelerometer to measure changes in the engine's acceleration, i.e., vibrations. 3. When engineers calibrate the knock sensor, they program the vibration pattern of knocking into the ECU. Once the knock sensor detects this vibration pattern, the ECU determines that the engine is knocking and immediately retards the ignition timing. Currently, more advanced knock sensors can even identify which specific cylinder is knocking and individually retard the ignition timing for that cylinder.
I've been driving for years and often encounter knocking issues. The symptoms are quite obvious: when accelerating, the engine makes a crisp metallic knocking sound, like a small hammer tapping, especially louder when climbing hills or under heavy load. The power tends to decrease, the accelerator feels sluggish, and acceleration isn't smooth; sometimes the car body shakes slightly, the fuel gauge drops quickly, indicating a significant increase in fuel consumption. The engine temperature may also rise, and touching the hood feels hot. Last time I ignored this sound, the car started smoking not long after, and repairing the engine cost me thousands. It's recommended to regularly change spark plugs and use higher octane gasoline for prevention; if knocking sounds occur, immediately reduce speed and go to a professional shop to check for carbon deposits or ignition timing. Ignoring it can lead to minor engine damage at best or a breakdown on the road at worst, which is really not worth it.
