What Causes the Engine to Stall After Releasing the Accelerator?
3 Answers
The reasons for the engine stalling after releasing the accelerator are: 1. Fuel pressure too low, air filter clogged, injector atomization leakage, improper idle adjustment, poor spark plug performance, air flow meter failure; 2. Internal engine injector dripping or clogging, circuit failure, or insufficient fuel injection; 3. Carbon buildup in the throttle. The accelerator is a control device for regulating engine power, part of the vehicle's fuel supply system. By adjusting the pedal's depression, it controls the throttle opening, regulates air intake, and the computer controls the fuel amount, thereby managing engine speed. Extended content: The function of the accelerator: By controlling the throttle opening of the carburetor, it regulates the cylinder's filling volume and the metered fuel flow of the fuel regulator, determining the engine's output power and generating thrust.
I encountered this issue while driving some time ago. The car ran normally when accelerating, but stalled immediately when releasing the throttle. This problem is usually related to the intake system - either excessive carbon buildup on the throttle body causing poor valve operation, or a stuck idle control valve. Last time I fixed it by cleaning the throttle body. Additionally, you should check the vacuum lines for leaks, as rubber hoses in older cars tend to deteriorate and crack. Air leaks can disrupt the air-fuel mixture ratio. A clogged fuel filter may also cause insufficient fuel supply, leading to stalling after sudden acceleration when the fuel system can't keep up. For sensors, pay special attention to whether the throttle position sensor is providing accurate data - incorrect readings will make the ECU unable to properly control fuel injection. It's best to fix such issues promptly, as sudden stalling at traffic lights can be extremely dangerous.
With over a decade of car repair experience, I've seen this issue in about 80% of cases caused by idle speed control valve problems. When you release the throttle, the engine should automatically maintain around 800 RPM, but if the valve is stuck or severely carbon-fouled, it drops until stalling. Incorrect air-fuel mixture could also be the culprit - either a clogged air filter restricting airflow or blocked injectors limiting fuel supply. Low fuel pump pressure affects performance too, especially when returning to idle after hard acceleration. The most elusive case I've encountered was a faulty crankshaft position sensor - when its signal cuts out, the ECU stops ignition completely. Start with simple checks: clean the throttle body and idle valve, then test if fuel pressure meets specifications. For older vehicles, oxidized wiring connectors might be the issue - try unplugging and reconnecting all connectors.
