S6 Rough Running and Power Loss Points to Fuel System

Having experienced near-identical symptoms on my 2015 A7, this sounds like a failing fuel injection system and possibly a faulty oxygen sensor disrupting the air-fuel ratio. The rough idle, power loss, and jerky acceleration match what I encountered. The issue turned out to be two defective fuel injectors that were not atomizing fuel properly. This created an inconsistent fuel spray pattern, leading to incomplete combustion. The check engine light was triggered by the oxygen sensor detecting irregular exhaust composition. This is a serious issue that requires prompt attention, as continued operation can damage the catalytic converter due to unburned fuel entering the exhaust system. The throttle body also needed cleaning during the repair since carbon deposits had accumulated from the poor combustion. The repair process involved: Electronic diagnostic testing, Fuel pressure testing, Removing and testing all injectors, Cleaning the fuel system, Installing new injectors, Resetting the engine management system Getting this fixed is critical. Poor fuel delivery can cause cylinder misfires and eventual engine damage if left unaddressed. The symptoms suggest your car likely needs similar intervention.

Those issues sound just like what my S6 went through last spring. The mass airflow sensor was sending incorrect readings, which messed with the fuel injection timing. After replacing both the mass airflow sensor and cleaning the intake manifold, the jerking and rough idle completely cleared up. The spark plugs were also inspected during the repair and two were found worn beyond spec, so those got swapped out too. The engine has been running smoothly since then. Did you end up getting yours fixed? Curious about the final cost and if youve had any other issues pop up since the repair?

Thanks for asking about the repair outcome. After seeing the mechanic, the mixture preparation error was completely resolved. The main culprit was indeed a defective injection valve that was causing irregular fuel delivery and throwing off the air-fuel ratio. The repair cost came to 515 Euro including parts and labor. The mass airflow sensor readings are now stable, and the engine management system is maintaining proper fuel mixture. The intake manifold is functioning as it should, with no more jerking or rough idle issues. Since the fix, the engine has been running perfectly, smooth acceleration, stable idle, and no check engine lights. The oxygen sensor readings confirm the mixture is now correct, and fuel consumption has actually improved slightly. No issues have surfaced in the months since the repair, suggesting it was definitely the right diagnosis and fix.

Following up on this thread, I finally got the car fixed last week. Found a highly recommended independent shop through a local owners group. The mechanic confirmed the rich mixture problem right away after hooking up the diagnostic tool. The throttle body was heavily contaminated and the intake manifold had significant carbon buildup, both contributing to the erratic performance. They did a thorough cleaning of both components and replaced two faulty fuel injectors that were causing uneven fuel delivery. The full service ran 890 Euro including parts and labor. Bit steep, but the difference in performance is night and day. No more jerking, stalling or check engine lights. The idle is perfectly smooth now and acceleration is crisp again. For anyone facing similar symptoms, getting a proper diagnosis early really helps prevent more expensive problems down the line. Running with bad injectors could have damaged my catalytic converter if left unchecked. Really glad I got it sorted before any major damage occurred.