What Causes the RPM to Suddenly Increase When Releasing the Throttle and Pressing the Clutch?
3 Answers
It may be an issue with the vehicle's throttle body. If the throttle body's opening and closing positions are inaccurate, it can cause the engine's RPM to suddenly rise and then fall after releasing the throttle. You can try cleaning the carbon deposits on the throttle body and check if the throttle body's opening and closing mechanism is damaged. Here is some relevant information about the clutch: 1. Location: The clutch is located inside the flywheel housing between the engine and the transmission. The clutch assembly is secured to the rear plane of the flywheel with screws, and the output shaft of the clutch is the input shaft of the transmission. 2. Operation: During driving, the driver can press or release the clutch pedal as needed to temporarily separate or gradually engage the engine and the transmission, thereby cutting off or transmitting the power from the engine to the transmission.
The other day I encountered this situation while driving - just as I released the accelerator and pressed the clutch, the tachometer suddenly spiked, which really gave me a scare! At the repair shop, they found the clutch position switch had failed. The mechanic explained that when you release the accelerator, the fuel supply should decrease, but the stuck switch sent wrong signals making the ECU think acceleration was still happening, causing idle speed to surge instead. This commonly happens in older vehicles or due to switch aging in humid conditions. Left unfixed, it not only wastes fuel but may cause engine overheating and piston damage. I immediately replaced the switch, and now everything's normal with smoother driving. I recommend regular maintenance checks to fix issues early and avoid dangerous driving situations on the road.
From my perspective, the root cause lies in a faulty idle control system. When you depress the clutch pedal, the engine load suddenly decreases. Normally, the idle air control valve should return to reduce RPM, but if it's stuck or clogged with carbon deposits, it can't fully close, allowing excess air intake. Coupled with inaccurate clutch switch signals misleading the ECU to maintain high fuel injection. Common culprits include a dirty idle valve or a malfunctioning throttle position sensor. I've experienced this once before - cleaning these components solved the issue. If ignored, excessively high idle can increase fuel consumption by over 10% and accelerate engine wear, which simply isn't worth it. Getting it inspected when you have time would be the smart move.
