Audi Q3 TDI Rough Idle and Acceleration Issues Fixed

I had very similar symptoms with my 2015 Audi Q5 TDI. Being someone with basic car maintenance experience, I first suspected an engine misfire, but it turned out to be an exhaust leak near the manifold that was causing the rough idle and uneven performance. The symptoms were identical, rough idle, jerky acceleration, and the engine would run unevenly, especially when pressing the gas pedal. The check engine light was also illuminated. I took it to a workshop where they performed a thorough diagnostic. The repair involved replacing some gaskets and a cracked section of the exhaust manifold. Total cost was 265 Euro including parts and labor. Since the repair, the engine has been running smoothly with no issues. Before giving more specific advice, could you share: Current mileage on your Q3? Are you noticing any unusual exhaust sounds? Does the rough idle get worse when the engine is warm or cold? Have you had the error codes read? If so, what are they? This information would help determine if your issue is similar to what I experienced with my Q5.

Thanks for sharing your experience. My Q3 has 164614 KM and had its last service 3 months ago where they changed the air filter and did a standard inspection. The rough idle is definitely worse when the engine is cold and gradually improves as it warms up. I have had the error codes read and they point to a fuel delivery issue. No unusual exhaust sounds that I can notice. I am suspecting it could be related to the fuel pump or possibly crankshaft sensor based on the error codes, though I will need a proper diagnosis to confirm. The spark plugs were replaced during the last service, so I doubt those are the issue. Has anyone else encountered these specific symptoms, particularly the cold-start roughness improving with warmup?

This does sound different from my exhaust manifold issue. Given the symptoms youre describing, especially the cold-start roughness that improves with warmup, plus the error codes pointing to fuel delivery, I strongly suspect its related to the fuel pump system. My Q5 actually developed a similar issue about 8 months after the exhaust repair I mentioned. The fuel pump was failing intermittently, causing very similar symptoms to what youre describing. The engine would run quite rough when cold and the performance would be jerky during acceleration, though it would somewhat stabilize once warmed up. The ignition system and oxygen sensor were tested but came back fine. The workshop confirmed it was indeed a faulty fuel pump. The repair cost was around 780 Euro including parts and labor. Since the fuel pump replacement, the engine has been running perfectly, no more cold-start issues or uneven engine performance. Given your mileage and symptoms, Id recommend getting the fuel pump system checked as a priority, especially since youve already ruled out simpler causes like spark plugs. Would definitely be worth having a professional diagnose it to confirm, as fuel pump replacement isnt a small job cost-wise.

Thanks for the input. After checking all the responses, I called a nearby workshop and made an appointment for next week. They mentioned the symptoms do align with potential fuel pump issues, which matches what most of you suggested. The timing works out well since I was planning to get the timing belt checked soon anyway, so they can inspect both while the car is in. They quoted roughly 850 Euro for a fuel pump replacement if needed, which seems in line with what others paid. Will update once I get the actual diagnosis and repair done. The cold-start roughness has gotten slightly worse over the last few days, so I am glad to be getting it looked at soon. Really helpful to hear from others who had similar issues, makes me more confident about what to expect from the repair process. Let me know if anyone else has additional tips regarding fuel pump replacement on these engines that I should discuss with the workshop when I take it in.