Audi S7 Stalling Mystery: Idle Control Valve Alert

Had the same issue with my 2014 Audi S5. The engine idle problems turned out to be severe carbon buildup in the air intake system and throttle body. The idle speed would fluctuate wildly before stalling, especially after cold starts. The initial diagnosis pointed to the idle control valve, but after a thorough inspection, the entire intake manifold was heavily contaminated. This is a common problem with direct injection engines. The throttle body cleaning alone was not sufficient, the intake ports required professional cleaning to restore proper idle control. The fix involved removing the intake manifold, cleaning all ports, and servicing the throttle body. After the service, the idle speed stabilized completely. This was a serious issue that needed immediate attention to prevent further engine performance problems. For your S7, recommend getting a second opinion from a shop specializing in VAG engines. Have them specifically check: Carbon buildup in intake ports, Throttle body function and cleanliness, Mass airflow sensor readings, Vacuum leaks around the intake system Your symptoms match exactly what happens when the air intake system gets contaminated. The check engine light typically indicates irregular idle speed in these cases.

Thanks for sharing your experience with the carbon buildup issue. My stalling engine problem was also resolved after a complete intake system cleaning. Makes sense that the throttle body and intake manifold were the root cause rather than the IAC valve I initially suspected. Question, do you recall roughly how much the complete cleaning service cost? Also, has the engine idle remained stable since the repair, or have you noticed any other issues pop up? Want to make sure I budget properly and know what to expect long term with my S7.

The cleaning service sorted out my S7 completely, it has been running perfectly stable since then. The mechanics found the idle air control valve was actually damaged due to the heavy contamination, so they replaced it during the service. The complete job including parts and labor came to 425 Euro, which covered the thorough intake system cleaning and the new IAC valve. The engine idle is now consistently smooth, especially during cold starts where it used to struggle the most. No stalling issues or check engine lights have appeared in the months since the repair. The air intake system now functions as it should, maintaining proper idle control in all conditions. Based on what the technician explained, regular intake cleaning helps prevent these issues from recurring. The carbon buildup that affects direct injection engines needs periodic maintenance to avoid future stalling problems and maintain optimal idle speed.

Thanks everyone for the detailed replies. Took my S7 to a different mechanic who confirmed the carbon buildup diagnosis. Got the full intake system cleaning done last week, including the throttle body service, total bill came to 460 Euro. The car runs amazingly well now. No more engine stalling issues and the idle speed is perfectly steady, even on cold mornings. The check engine light disappeared right after the service. Really wish I had known about this common problem with direct injection engines earlier, would have saved me some headaches. The new shop did a great job explaining everything and showing me the carbon deposits they cleaned out. They recommended doing this service every 60000km to prevent future buildup and idle control problems. Money well spent considering how much better the car runs now. Just wanted to close the loop here in case anyone else runs into similar stalling symptoms with their vehicle. Sometimes the simple solution of a thorough cleaning is all it takes.