I’m currently driving a 2014 Toyota Prius Alpha and have been experiencing an issue. When I release the accelerator pedal, the car surges unexpectedly. Additionally, while in park, the engine RPM fluctuates. During these surges, the hybrid system stops charging. There are no fault codes displayed. Do you have any advice on how to resolve this? Here are the diagnostic steps I’ve already tried without success: Removed and cleaned the throttle body and airflow sensors Disconnected the airflow sensor and O₂ sensor Removed the intake manifold and replaced the manifold gasket Cleaned the EGR internal passage Cleaned the PCV valve Verified air-fuel ratio sensor and O₂ sensor values (all within range) Observed throttle idle switching on and off Noted that catalyst temperature was slightly high Any guidance or suggestions would be greatly appreciated.
Can you elaborate on what you mean by 'surges'? By how much does the RPM fluctuate, and on what sort of time scale? The car does not constantly charge the traction battery. When it is adequately charged, the car stops sending charging current to it, which reduces the load on the engine, which is a change that can be heard. From what you have said so far, I am not able to be sure whether you are describing normal behavior or something worth being concerned about.
Is the behavior you're describing a change from previous normal behavior, or have you not had the car long enough to be familiar with normal behavior? When the car is in Park, the engine normally shouldn't be running at all, much less surging, unless the engine is cold, the battery has been discharged down to two "bars" or less on the charge level display, or you're in maintenance mode.
