S7 Cold Start Rough Idle, Failed Injector Warning Signs

As an S6 owner with a similar TFSI engine from 2018, I encountered nearly identical fuel injection symptoms. The rough idle during cold starts pointed to injector issues, which was confirmed through proper diagnostic testing. The key signs were: Rough idle specifically during cold starts, Engine struggling to maintain stable RPMs, Occasional hesitation when accelerating A qualified shop performed a comprehensive fuel system diagnosis including: Pressure testing of the fuel injection system, Electronic injector signal testing, Flow rate measurement for each injector The testing revealed two faulty injectors causing uneven fuel distribution. The repair required replacing the problematic injectors and performing a complete fuel system cleaning. This resolved the cold start problems and restored proper idle. For proper diagnosis, request specific injector performance data rather than relying on general scan tool readings. Modern direct injection systems are sensitive, and cold start problems often trace back to injector deposits or internal wear. This was a serious issue requiring specialized testing equipment and expertise to properly diagnose and fix. Throwing parts at the problem without proper testing could lead to unnecessary replacements and continued issues. Best to have documented flow rates and electrical readings for each injector before replacing components.

Thanks for sharing your experience. I had the exact same symptoms with my Audi S7 last winter. The engine misfire during cold starts was really concerning. Had the complete fuel system tested and it turned out the fuel rail pressure sensor was acting up along with a clogged injector affecting fuel delivery. Would be helpful to know what you ended up paying for the diagnostic and repair work? Also, have you experienced any similar issues since the fix was done? In my case, I had to get the entire fuel rail assembly cleaned as a preventive measure, which made a noticeable difference in cold start performance.

Thanks for asking about the repair costs and follow-up performance. After getting a comprehensive fuel system diagnosis, the testing confirmed a faulty cold start injector causing the rough idle and starting issues on my S6. The repair bill came to 515 Euro which covered replacing the defective injection valve and performing a thorough fuel system cleaning. Since having the work done, the cold start problems have completely resolved. The engine fires up smoothly even in cold conditions, and the erratic idle is gone. The fuel delivery is now consistent, and I have not experienced any similar issues in the months following the repair. The diagnostic testing was crucial in pinpointing the exact injector that was malfunctioning rather than replacing multiple components unnecessarily. Having the fuel rail and injectors professionally cleaned as part of the service seems to have helped maintain optimal performance. The investment in proper diagnosis and repair has definitely paid off in terms of reliable cold starts and smooth operation.

Thanks everyone for the helpful input. Finally got my S7 looked at by a different shop that specializes in fuel injection diagnostics. The comprehensive injector test revealed two problematic injectors causing the rough idle and cold start issues. The total cost came to 890 Euro including: Full diagnostic testing, Replacing both faulty injectors, Complete fuel system cleaning, Labor The repair took about 6 hours but the results were worth it. The engine misfire is completely gone and cold starts are smooth again. The technician showed me the flow rate data that confirmed the old injectors were definitely causing the fuel delivery problems. Really glad I got proper testing done instead of just replacing parts out of nowhere. The engine runs like new now and maintains steady idle even in cold weather. Will definitely keep up with regular fuel system maintenance to prevent similar issues in the future.