What is the reason for the engine speed dropping to idle when releasing the accelerator?

[MiguelMarie]

When releasing the accelerator, the engine speed drops to idle due to carbon deposits causing incomplete combustion of gasoline, leading to engine vibration issues. Below is an introduction to engine-related content: 1. Energy conversion: An engine is a machine capable of converting other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric motors, etc. For example, internal combustion engines typically convert chemical energy into mechanical energy. 2. Device: The term 'engine' can refer to both the power generation device and the entire machine including the power unit (e.g., gasoline engines, aircraft engines). The engine was first developed in England, so the concept of an engine originates from English, with its original meaning referring to 'a mechanical device that generates power.'

[LaAutumn]

I remember one time when I was driving my old car, as soon as I released the accelerator, the RPM dropped like diving to idle speed, almost causing me to stall at the intersection. With more experience, I found that this is often related to the idle control system. If the motor or valve of that system is clogged with carbon deposits, or if the sensor is inaccurate, the engine mistakenly thinks it needs to drop to the lowest RPM. Other possibilities include an intake pipe leak letting in too much air, or a faulty throttle position sensor sending incorrect signals to the computer. If these components aren't cleaned regularly, the problem will occur frequently. I suggest not waiting when encountering similar situations; unstable RPM at high speeds may cause jerking and increase the risk of accidents. During regular maintenance, request an inspection of the idle valve. Spending a little money on cleaning is much more cost-effective than major repairs.

[EmeryRose]

I enjoy tinkering with my car in my spare time. When encountering a situation where the RPM drops to idle upon releasing the throttle, the first things to check are the idle control valve and the throttle body. First, park the car safely and disconnect the power, then open the hood and remove the control valve. Use carburetor cleaner to spray off any carbon deposits and see if that helps. If not, check the vacuum hoses for cracks or leaks, or use a multimeter to measure the resistance of the throttle position sensor to ensure it's within the normal range. Also, loose wiring harness connectors can often cause issues, so make sure they're securely fastened. For prevention, I clean these components myself every six months to avoid idle valve sticking. Smooth RPM and gear shifts make for a more pleasant drive, especially in city traffic jams, where erratic idle can be particularly frustrating.

[DelLeah]

As an ordinary car owner, I also experienced a sudden drop in RPM when releasing the throttle, which gave me a scare. Later, I learned that a faulty idle control unit could cause this, such as when sensor signal disruptions lead to incorrect computer judgments. The daily impact is significant, with noticeable jerking in automatic transmission cars and a tendency to stall on slopes, causing trouble. If this happens while driving, it's recommended to operate gently to ensure safety and avoid sudden acceleration. During regular maintenance, have the shop check the coolant temperature sensor and ECU connections, as these details can prevent most faults.

[LailaFitz]

From an electronic control perspective, the engine RPM dropping to idle when releasing the throttle is often caused by throttle position sensor drift or idle air control valve malfunction. When the ECU fails to receive accurate signals, it commands the engine to reduce to preset idle speed. Wiring shorts or relay aging can also interfere with control. Diagnosis requires professional tools to read data streams and compare with actual positions. Preventive maintenance includes updating ECU software and ensuring sensors are free from dust interference. Ignoring this issue may lead to increased fuel consumption or excessive emissions, so timely repair is more cost-effective.

[DiElizabeth]

After driving for over a decade, I've found that most idle speed issues stem from inadequate maintenance. Rapid RPM drop after releasing the throttle is usually caused by carbon buildup in the throttle body or a contaminated idle air control valve, leading to uncontrolled air intake. For prevention, I clean the throttle body every 20,000 kilometers using high-quality cleaner to remove sludge. Check sensor connections for rust and inspect vacuum hoses for aging cracks. Developing good habits like minimizing frequent short-distance start-stop cycles can reduce carbon deposit risks. With proper vehicle maintenance, stable RPM ensures confident and safe driving.