Engine surging at idle in your 2017 Kia Soul accompanied by a P0507 code indicates idle speed exceeds normal parameters. The surging sensation occurs as the engine control module attempts to bring RPM down from an unexpectedly high level, fighting against whatever condition is causing elevated idle.
Understanding P0507
P0507 triggers when idle speed remains above the expected target, typically 200+ RPM higher than normal for an extended period. The Soul's electronic throttle control system manages idle speed precisely, so persistent high idle indicates an issue overwhelming the system's corrective capability.
Surging Mechanism
The surging you feel results from the ECM continuously adjusting throttle position and fuel delivery attempting to lower RPM. When a vacuum leak or sensor issue provides conflicting information, the corrections overshoot, creating the rhythmic rise and fall characteristic of surging.
Common Causes
Vacuum leaks at the intake manifold, PCV system, or brake booster introduce unmetered air raising idle. The throttle body may be dirty, preventing proper closure. A sticky or contaminated idle air control passage affects idle regulation. The throttle position sensor may provide incorrect closed-throttle readings.
Electronic Throttle Considerations
The 2017 Soul uses electronic throttle control where the accelerator pedal sends signals to the ECM, which controls throttle opening. This system requires proper calibration and can malfunction if the throttle body is contaminated or sensors provide incorrect feedback.