RS5 Cold Start and Rough Idle Issues Need Fixing

The symptoms you describe with your RS5 match what I experienced with my 2018 S5. The hard starting and rough idle, particularly during cold starts, are classic signs of fuel injection issues. My vehicle showed similar symptoms, poor engine performance and misfire conditions until reaching operating temperature. After proper diagnosis, the problem was traced to a faulty fuel injector that was not atomizing fuel correctly during cold starts. The repair involved replacing two injection valves that had developed internal wear. This is typically a serious issue that requires prompt attention, as faulty injectors can lead to increased fuel consumption, reduced performance, and potential damage to other engine components. The diagnostic process included pressure testing the fuel system and using specialized equipment to measure injector spray patterns. The repair resolved the hard starting issues and eliminated the rough idle completely. The engine returned to smooth operation, even during cold starts. While the job requires removing several components to access the fuel system, its absolutely necessary for proper engine function. When dealing with fuel injection problems, its crucial to have proper diagnostic equipment and expertise, as symptoms can sometimes mimic other fuel system issues.

Thanks for sharing your S5 experience. The symptoms match my RS5 perfectly. Rough idle and cold start problems were driving me crazy until I got it fixed. Did you have any other fuel delivery problems since the repair? Just curious if replacing those injectors solved everything long term. My fuel rail is scheduled for inspection next week and Id like to know what costs to expect for the injector test and potential repairs.

Had my injector issue fixed last week and the cold start problems disappeared completely. The faulty cold start injector was causing all those hard starting symptoms, exactly as suspected. Total repair cost was 515 Euro for replacing the defective injection valve. The fuel delivery system has been running flawlessly since the repair. No more rough idle or starting issues, even on the coldest mornings. Getting proper injector cleaning and testing done during the service was key to identifying the exact problem. For your upcoming fuel rail inspection, make sure they perform a complete pressure test of the fuel system. A thorough diagnostic check on injector spray patterns will help catch any potential issues early. The testing process itself usually takes a few hours since they need to check each injector individually. Would definitely recommend getting the full fuel system inspection done, even if it costs a bit more upfront. Proper diagnosis helps avoid replacing parts unnecessarily and ensures the repair fixes the root cause.

Thanks for the helpful advice. Finally got my RS5 back from the shop after dealing with those frustrating fuel injection issues. The mechanic found two faulty injectors causing my cold start problems and rough idle. The diagnostic process was thorough, they ran a complete injector test and fuel pressure check. Total bill came to 890 Euro including parts and labor. More than expected but worth every cent since the car runs perfectly now. No more shaking or stuttering during cold starts. The repair took about 6 hours since they had to remove several components to access the fuel system properly. Engine starts smoothly and maintains steady idle even in cold weather. Such a relief to have this fixed by a competent shop that actually diagnosed the problem correctly. Really glad I asked here first and learned what to look for. Having the right diagnostic work done from the start saved me from throwing parts at the problem like my previous mechanic wanted to do.