Audi A7 Rough Idle Fix: Spark Plugs vs Fuel Injectors

Having some experience with engine issues, I faced almost identical symptoms with my Audi A6 2012 last year. The rough idle and jerking during acceleration turned out to be caused by a leak in the exhaust system, which was affecting the oxygen sensor readings and causing engine misfire issues. After multiple attempts to diagnose it myself, I took it to a workshop where they performed a smoke test and found the exhaust leak. The total repair came to 265 Euro, including parts and labor. The fix made a huge difference, the rough idle disappeared completely and the engine ran smoothly again. Before jumping to conclusions about fuel injectors or spark plugs, it would help to know: What engine size does your A7 have? Have you noticed any unusual exhaust sounds? Are there any other warning lights besides the check engine light? When was your last air filter change? The symptoms you describe could indeed be related to fuel delivery or ignition, but based on my experience with a similar model, having the exhaust system checked should be high on the diagnostic list. A proper diagnosis with a scan tool would reveal if the crankshaft sensor or oxygen sensor readings are being affected.

Thanks for sharing your experience. My A7 2010 has now reached 71282 KM and was last serviced 3 months ago. After reading your reply, I checked and there is a slight ticking sound from the exhaust area. Also noticed the car runs worse when cold. I just pulled the diagnostic codes and got P0303 and P0300, pointing to engine misfire issues. The service history shows the spark plugs were never changed, so they are definitely due for replacement. Going to have them check the ignition coils too since they commonly fail together. Could you share how long the repair took in your case? Planning to book it in next week and need to arrange transportation.

Thanks for the additional details. On my A6, the entire repair process took about 4 hours, though yours might be different since it seems your issue is likely spark plug and ignition coil related rather than the exhaust leak I experienced. Those misfire codes (P0300 and P0303) combined with the original symptoms and cold running issues strongly suggest worn spark plugs and possibly failing ignition coils. Since your spark plugs have never been changed at 71282 KM, they are well overdue for replacement. Most manufacturers recommend changing spark plugs every 60000 KM. When I had similar misfiring issues in another car years ago, replacing both the spark plugs and ignition coils resolved the problem completely. The repair should take about 2-3 hours if they are just replacing spark plugs and coils. The parts typically cost around 180-250 Euro for a complete set. A useful tip: have them inspect the air filter while they are working on it. A clogged air filter can contribute to rough running, especially during cold starts, and its often overlooked during regular maintenance. Also, since the engine misfire has been ongoing, it would be wise to have them check the timing belt condition while they are in there, as prolonged misfiring can sometimes cause additional wear.

Thank you everyone for the advice. After getting those misfire codes and hearing about the similar experiences, I feel more confident about what needs to be done. Will definitely have them replace both the spark plugs and check the ignition coils since neither have been changed at 71282 KM. The timing belt inspection is a good suggestion too given the mileage. I have booked the car in for next Tuesday and arranged for a rental. The shop quoted around 220 Euro for parts plus labor, which seems reasonable based on what others paid. They estimated 2-3 hours for the full job including diagnostics. Will update the thread once I get it back and let everyone know if changing the spark plugs and ignition coils fixed the rough idle and jerking issues. Really appreciate all the detailed responses and tips about checking the air filter too.