What is the reason for the engine speed not dropping when releasing the throttle?
4 Answers
The reason for the engine speed not dropping when releasing the throttle is: the throttle spring has been in a compressed state for a long time, resulting in reduced tension, increased throttle opening, and increased fuel supply, causing the speed indicator to return slowly. It could also be due to faulty components or air leakage in the intake manifold. If the vehicle has just undergone maintenance, a slow drop in engine speed is not considered a fault. The engine speed affects the number of work cycles per unit time or the effective power output of the engine, meaning the engine's effective power varies with different speeds. For the same engine model, the rated power value may differ depending on its application, and the effective torque also changes with engine conditions. The maximum torque output and its corresponding speed are used as indicators to evaluate the engine's performance in automotive applications.
My old car had this issue before where the RPM would stay high after releasing the throttle and wouldn't drop, which was really annoying. The cause might be the throttle pedal itself not resetting, possibly due to a stuck or aged spring, making it feel rough when pressed. On the electronic side, if components like the throttle position sensor or idle control valve have too much carbon buildup or a short circuit, the ECU might misjudge and keep supplying fuel to maintain high RPM. Later, I found a vacuum leak during inspection—inaccurate air intake affected RPM control. Also, poor transmission matching can cause chaotic shift logic, which may keep RPM elevated. Don't delay fixing this, as it wastes fuel and accelerates component wear. I suggest first checking pedal rebound, then using an OBD scanner to read trouble codes, or directly sending it for repair to diagnose electronic and mechanical issues.
After driving many cars, I've noticed that the RPM not dropping when releasing the throttle is often an engine control issue. It could be an erroneous throttle position sensor signal, or the ECU failing to promptly respond to reduce fuel injection. Vacuum leaks are also common culprits, such as cracked hoses or loose connections allowing extra air to disrupt idle. Additionally, carbon buildup in the throttle body or intake system can block airflow feedback. Once, my car had this problem, causing erratic idle and black smoke. Considering safety, prolonged high-RPM driving increases overheating risks and fuel consumption. The best approach is regular maintenance to clean the throttle body and immediately seek professional electronic diagnostics at a shop when abnormalities are detected.
If the engine RPM gets stuck and doesn't drop when you release the throttle, it's most likely a fault in the idle control system. For example, the idle control motor might be clogged or stuck, preventing proper air flow regulation. The pedal linkage mechanism could also have excessive play or insufficient lubrication causing sticking. Alternatively, sensors like the MAF sensor might be inaccurate, sending incorrect data to the control unit. My relative's car once had this issue, making acceleration jerky and unsafe. Remember to check if any fuses are blown affecting the circuit. If the problem persists, seek help from a professional mechanic rather than attempting DIY repairs to avoid short circuits or accidents.
