Audi A3 Fuel System Troubles: Misfires and Stalling Fix

I experienced very similar issues with my 2014 Audi A4, and the symptoms match exactly what you describe, engine misfire, stalling, and jerky acceleration. After some initial troubleshooting, I took it to a workshop since I have only basic car maintenance experience. The problem turned out to be much simpler than expected. The technician found a loose connection in the wiring harness going to the fuel pressure sensor. The poor connection was causing erratic fuel delivery readings, making the engine management system behave unpredictably. The fix involved properly securing the connection and replacing a damaged plug. Total cost was 95 Euro including diagnostic time. Since the repair, the engine runs smoothly with no issues in fuel delivery or engine performance. To provide more specific advice for your case, could you share: Current mileage on your A3, When did these symptoms first appear, Are the issues constant or do they occur intermittently, Have you noticed any changes in fuel economy, Are there any other warning lights besides the check engine light This information would help determine if your issue is similar to what I encountered or potentially something different in the fuel system.

Thanks for sharing your experience. My A3 has 182808 KM and just had its annual service last month. The rough idle and engine misfire started intermittently about 2 weeks ago. The symptoms occur more frequently when the engine is warm. After reading your reply, I checked the wiring connections, but they seem secure. I also noticed the fuel consumption has increased by about 15% lately. The check engine light is the only warning shown on the dash. Given that my symptoms persist even with good connections, Im suspecting either a failing fuel injector or fuel pressure regulator. The constant misfiring and poor fuel economy seem to point in that direction.

Looking at your latest update, your symptoms do sound different from my A4 case, especially with the increased fuel consumption and symptoms worsening with engine temperature. While my issue was a simple wiring fix, your fuel system might have a more substantial problem. Based on the symptoms you describe, particularly the 15% increase in fuel consumption combined with warm engine misfires, Im leaning towards a faulty fuel pressure regulator rather than injectors. When my A4 had a bad injector last year, it showed more consistent symptoms regardless of engine temperature. The fact that your check engine light remains on even after checking connections suggests an actual component failure rather than a loose connection like in my case. The fuel pressure regulator is a common failure point in these engines, and the symptoms align with what you describe. A failing pressure regulator cant maintain proper fuel system pressure, leading to: Rich fuel mixture causing higher consumption, Irregular fuel delivery causing misfires, Rough idle and performance issues, Worse symptoms when warm due to pressure variations Since your car just had service, maybe check if the fuel filter was replaced. A clogged filter can create similar symptoms by restricting proper fuel flow to the pressure regulator. Would strongly recommend getting the fuel pressure tested. Most shops can do this quickly and it will definitively show if the pressure regulator is the culprit.

Thanks everyone for the helpful insights. After reading through the responses, I went ahead and had the fuel pressure tested at a local shop. They confirmed the fuel pressure regulator was indeed failing, showing inconsistent pressure readings especially at operating temperature. The mechanic found the pressure would drop below spec when the engine got warm, explaining why the rough idle and misfires got worse after driving. They replaced the fuel pressure regulator and also changed the fuel filter since it was due for replacement anyway. Total repair cost was 380 Euro including parts and labor. The car now runs perfectly, no more misfires, stalling, or jerky acceleration. Fuel economy has also returned to normal levels. Really glad I checked here first as it helped me better understand the fuel system issues before going to the shop. The symptoms matched exactly what others described for a failing pressure regulator.