Rough A5 TFSI: Fuel System Issues Hit Performance

I had a very similar issue with my 2013 A4 2.0 TFSI. As someone with moderate experience working on these engines, I can tell you these symptoms are classic signs of injector problems. The check engine light came on in my case too, and the engine was running very rough. After multiple diagnostic tests, my workshop found that one of the injection valves was defective, causing uneven fuel distribution. This explained the power loss and rough idle perfectly. The repair involved: Complete diagnostic testing, Replacing the faulty injector, Recalibrating the fuel injection system, Testing all mass airflow sensor readings Total cost was 515 Euro, including parts and labor. The repair completely resolved the symptoms, and the engine has been running smoothly since then. Before suggesting specific solutions for your case, it would be helpful to know: Have you done any recent diagnostic scans? Are there any specific error codes showing? Did these symptoms appear gradually or suddenly? Have you noticed any unusual fuel consumption? Any recent maintenance or repairs performed? With these details, I could provide more targeted advice based on my experience with a very similar engine setup.

Latest service was done at 144000 KM last month. Thanks for the detailed response. Following up on your questions: The check engine light started flashing intermittently last week before staying on permanently. The diagnostic scan showed error code P0301, indicating cylinder 1 misfire. The rich mixture smell is quite noticeable, and fuel consumption has increased by about 20%. I checked the spark plugs and found them covered in black carbon deposits. No major repairs done recently besides regular oil changes and filter replacements.

Thanks for providing those additional details. The P0301 code and carbon-fouled spark plugs on your A5 align perfectly with what I experienced on my A4 before discovering the underlying issue. The black deposits on your spark plugs combined with the rich fuel smell strongly suggest an overly rich air-fuel ratio, which matches my previous diagnosis. However, in my case, after initially suspecting just the injectors, we found the mass airflow sensor was also malfunctioning, causing incorrect fuel mapping. My repair actually ended up including: Cleaning the mass airflow sensor, Replacing all spark plugs (they were similarly fouled), Testing and replacing the faulty injector, Performing a full fuel system cleaning The total repair came to 680 Euro, slightly more than initially quoted, but solved all issues: No more check engine light, Proper fuel consumption restored, Smooth idle and acceleration, No more misfires Given your symptoms mirror mine so closely, especially the P0301 code and fouled plugs, Id strongly suggest having both the fuel injection system and mass airflow sensor thoroughly tested. The carbon deposits are a clear sign the air-fuel ratio is off, just like in my case.

The symptoms and solutions you outlined match perfectly with what I'm experiencing. I will definitely have both the mass airflow sensor and injection system checked. The black deposits on my spark plugs combined with the rich mixture smell and P0301 code point strongly toward a similar underlying issue. I will schedule a diagnostic appointment to have everything thoroughly tested, particularly focusing on the intake manifold, throttle body, and complete fuel delivery system. The fact that cleaning your mass airflow sensor and replacing the fouled spark plugs resolved similar issues gives me a clear direction for repairs. 680 Euro seems reasonable for the complete fix, especially considering the comprehensive nature of the repairs needed. Will update once I get the diagnostic results and complete the necessary repairs. Thanks for sharing your experience, its been extremely helpful in narrowing down the potential causes.