A8 Rough Acceleration Points to Rich Fuel Issue

Last year I experienced nearly identical symptoms with my 2013 Audi A7. The check engine light came on, accompanied by rough acceleration and noticeably poor fuel economy. The diagnostic scan revealed issues with multiple fuel injectors failing to deliver proper air-fuel ratio. The fuel injectors had carbon buildup and were not atomizing fuel correctly, leading to rich mixture conditions. After replacing all affected injectors and cleaning the intake system, the engine performance returned to normal. The catalytic converter also showed early signs of damage from the rich fuel mixture, but fortunately did not require replacement. This is typically a serious issue that should be addressed promptly, as continued operation can lead to: Catalytic converter failure, Further decreased fuel economy, Potential engine damage, Failed emissions tests Suggest checking: 1. Air filter condition 2. Fuel injector operation 3. Oxygen sensor readings 4. Intake system for carbon deposits Important to have proper diagnostics done, as similar symptoms can also indicate other fuel system issues. Would recommend finding a shop specializing in Audi fuel injection systems for accurate diagnosis.

Thanks for your detailed reply about the injector issues. Was dealing with these exact problems on my A8 a few months back. The check engine light and rough acceleration were really concerning. My mechanic also found rich mixture issues but in my case it turned out the air filter was completely clogged plus one faulty oxygen sensor was throwing off the air-fuel ratio readings. Do you remember the total cost for your repairs? In my situation I got lucky, just needed the air filter replacement and new O2 sensor. Any issues popping up since the fix? The catalytic converter damage you mentioned has me worried about checking mine too.

The injector repairs on my A7 cost 515 Euro total, which covered diagnostics and replacing the faulty fuel injectors. Since fixing the rich mixture problem, the engine has been running perfectly, no more sluggish acceleration or excessive fuel consumption. The fuel economy is back to normal and the check engine light has stayed off. Getting it fixed promptly helped prevent permanent damage to the catalytic converter, which would have been much more expensive to replace. Given your air filter and O2 sensor issues were resolved, keep monitoring your fuel consumption patterns. If your intake manifold is clean and fuel injectors are working correctly, you should be fine. Regular maintenance helps catch these fuel system problems before they affect other components. Our cases show how important proper diagnostics are, similar symptoms can stem from different root causes in the fuel delivery system. The investment in fixing the rich mixture condition early definitely saved money in the long run by protecting the catalytic converter and other engine components.

Thanks for the helpful advice. After my initial post, I took my A8 to a different mechanic who actually knew what they were doing. The check engine light and rough running were making me nervous, but the diagnostic showed exactly what we discussed, clogged air filter and bad oxygen sensor causing rich mixture problems. Total repair came to 280 Euro including parts and labor. They showed me the completely blocked air filter and explained how the faulty O2 sensor was messing up the fuel mixture. Since the fix, the car runs smooth again and fuel economy is back to normal. Really glad I caught it before any catalytic converter damage happened. The new shop also did a thorough check of the fuel injectors and intake, everything else looked clean. Been about 2 months now with no issues. Going to stick with this mechanic from now on since they actually took time to properly diagnose the problem instead of just guessing.