Willanda felt the engine push forward when she refueled the door.

The reasons are too much carbon deposition in the first throttle or engine, O2 sensor failure, fuel nozzle leakage in the third quarter, engine knocking in the fourth quarter, and poor fuel quality.

The solution is to clean the throttle or the inside of the engine, replace the oxygen sensor, replace the fuel injector of the engine and replace the higher grade fuel.