A5 Engine Trouble: Lean Mix Causing Power Loss

Had nearly identical symptoms on my A4 2010 at 42000 KM. The diagnosis revealed faulty fuel injectors causing improper fuel delivery. The rough running and weak acceleration happened because the engine was getting inconsistent fuel spray patterns. The repair involved replacing two fuel injectors and cleaning the throttle body since carbon deposits had accumulated. The intake manifold also needed attention due to the uneven fuel distribution that occurred over time. This is considered a serious issue since bad fuel injectors can lead to catalytic converter damage if left unchecked. The lean condition puts extra stress on engine components and continued driving could cause more expensive problems. The entire repair process took about 6 hours at the shop. They needed specific diagnostic equipment to properly test and calibrate the new injectors. The spark plugs were also replaced as a preventive measure since they showed signs of running lean. Getting this fixed promptly is important. The symptoms you describe match closely with failing injectors, and continuing to drive could result in more extensive engine damage.

Thanks for sharing your experience. I had very similar issues with my A5 last year. The symptoms you described with the fuel injectors match what I went through, especially the jerky acceleration and check engine light coming on. The oxygen sensor was also faulty in my case, which contributed to the lean running condition. Was the repair cost significant for you? In my situation, it ended up being quite an expense. Also curious if youve had any other issues pop up since the repair? Sometimes these fuel system problems can be connected to other components like the mass air flow sensor.

Since getting the fuel injectors fixed, my A5 has been running perfectly. The repair shop diagnosed and replaced a faulty injection valve that was causing the lean fuel mixture. The total cost came to 515 Euro which included parts and labor. The air-fuel ratio is now correctly balanced, and the engine response is smooth with no more jerking during acceleration. The mass air flow sensor readings are normal, confirming the fuel delivery system is working as intended. What really made the difference was replacing that problematic fuel injector. The repair shop showed me how the old one was causing inconsistent spray patterns, leading to the lean running condition. They also performed a thorough system check to ensure no related components were affected. The car now climbs hills effortlessly, and the check engine light has stayed off. No other issues have emerged in the fuel system since the repair. The intake manifold pressure readings are stable, indicating everything is functioning properly.

Thanks for the advice. After reading about similar experiences, I took my A5 to a different mechanic this time. They found two failing fuel injectors and a worn oxygen sensor causing the lean condition. The total repair came to 680 Euro including parts and labor. The whole job took about 5 hours. They showed me the old parts, the injectors were pretty badly clogged and the oxygen sensor was giving inconsistent readings. They also cleaned the throttle body while they were in there since it had some carbon buildup. The difference in performance is amazing. The engine runs smooth now, acceleration is crisp with no jerking, and it handles hills like new again. The check engine light is finally off and staying off. Really glad I got this fixed before it caused more damage. The mechanic explained everything clearly and showed me all the replaced parts. Much better experience than my previous shop. If anyone else runs into similar symptoms, definitely get it checked out quickly before it gets worse.