Why does the engine stall without throttle but runs when throttle is applied?

[Trent]

Specific reasons include the following: 1. Fuel system malfunction: During normal operation, the fuel pump draws fuel from the tank, passes it through the filter into the distribution line, and then sprays it out through the injector to form an air-fuel mixture. In this process, the fuel pump and injector are the most prone to failure, followed by filter and fuel line blockages. If necessary, the fuel system can be cleaned. To reduce such occurrences, always refuel at reputable gas stations with the correct grade of gasoline and ensure timely refueling to avoid letting the fuel level drop below the red line. 2. Throttle body blockage: The throttle body is undoubtedly the most critical component and also the most susceptible to issues. Typically, maintenance personnel will consider cleaning the throttle body. However, if frequent cleaning does not fully resolve the stalling issue, it usually indicates a fault. Additionally, check the vacuum pump to ensure normal air intake. 3. Abnormal spark plug ignition: In a gasoline engine, the combustible mixture is ignited by the spark plug near the top dead center of compression. Therefore, when the spark plug fails, it naturally leads to engine stalling. In such cases, replacing the spark plug is recommended. If replacement is inconvenient, temporary solutions like cleaning the electrodes or adjusting the central electrode length can be used. Other factors like insufficient battery voltage, leakage, faulty ignition coil, or wiring issues can also cause poor ignition or stalling. 4. Sensor malfunction: Check if all sensors and actuators are functioning properly. Key sensors include the throttle position sensor, oxygen sensor, and crankshaft position sensor. If the crankshaft position sensor has been replaced, also check if the oxygen sensor is contaminated.