Why does the car rev without pressing the accelerator when starting?
2 Answers
The reason why the car revs without pressing the accelerator when starting is due to a problem with the idle speed motor. It is necessary to check the idle speed motor and clean the throttle body. The car accelerator is a device on the internal combustion engine that regulates the fuel supply. During driving, the driver adjusts the amount of pedal press to control the engine's air intake, thereby regulating the engine speed. The steps for starting a car are: 1. Press the start button, and after the ACC light comes on, press it again for the vehicle to perform a self-check; 2. Press the brake, then press the one-button start to ignite and start the engine; 3. Release the foot brake and let the car warm up in place; 4. Press the foot brake, shift to D gear, and release the handbrake; 5. Slowly release the foot brake, add some throttle, and the start is complete.
Last time I encountered this issue, I found the throttle body was too dirty. When starting the car, the ECU increases idle speed for quick warm-up. But if carbon buildup in the throttle body is severe, the throttle plate may stick in a more open position, allowing excess air to enter and causing engine revving. Another possibility is the idle control valve being stuck by sludge and unable to return to position, or the coolant temperature sensor falsely reporting low temperature signals causing the ECU to continuously enrich the mixture. My old car improved immediately after cleaning the throttle body, and I also checked the vacuum lines for leaks. This problem is particularly noticeable in winter, and short-distance driving makes carbon buildup more likely. I recommend checking it every 20,000 kilometers or so.
