Rough Cold Start Fix: Audi TT TFSI Injector Guide

Had a similar issue with my 2006 Audi A4 2.0 TFSI. As someone with some experience working on cars, I initially thought it was just a fuel delivery problem, but it turned out to be more complex. The symptoms matched yours exactly, hard starting in the morning and a really rough idle until the engine reached operating temperature. The fuel system would eventually stabilize, but those first few minutes were concerning. After multiple attempts to clean the fuel rail and injectors with additives, I finally took it to a workshop. Their diagnostic showed a faulty fuel injector that wasnt atomizing properly during cold starts. The mechanic explained that when cold, the injector wasnt opening and closing correctly, leading to inconsistent fuel delivery. The repair included: Replacing the defective injector, Cleaning the entire fuel system, Testing fuel pressure at the rail Total cost was 515 Euro including parts and labor. The problem completely disappeared after the fix. No more rough idle or hard starting issues. Before suggesting specific solutions, could you share: Current mileage on your TT? Any check engine lights? Have you noticed any fuel consumption changes? Are there any other symptoms when the engine is warm?

Latest service was at 35100 KM, about 2 months ago. Thanks for sharing your experience. I have also noticed slightly higher fuel consumption lately, around 0.5L/100km more than usual. The check engine light flickers occasionally during cold starts but turns off once the engine warms up. Running a fuel injector test might help pinpoint if thats really the culprit. When warm the engine runs perfectly smooth, its just those first 3-4 minutes that are problematic. Was quoted 580 Euro for a full fuel rail inspection and injector replacement if needed, but wanted to get some community feedback before proceeding. No other symptoms present during normal operating temperature. Would fuel system cleaner be worth trying first before going for the full repair?

Thanks for those extra details, experiencing almost identical symptoms to what I had. That flickering check engine light during cold starts is particularly telling, as it matches exactly what my A4 was doing before the repair. The fuel consumption increase you mentioned tracks with my experience too. Before fixing my injector issue, I was seeing about 0.6L/100km higher consumption. Engine misfire during those first few minutes is likely causing that extra fuel usage. While fuel system cleaners might help with minor carbon buildup, they probably wont resolve what sounds like a failing injector. I wasted about 50 Euro on various cleaners before finally getting the proper repair. The quote of 580 Euro youve received is in line with what I paid (515 Euro). The fuel rail inspection is worth doing, when they checked mine, they found the injector wasnt maintaining proper pressure during cold starts, leading to the rough idle and starting issues. Given your symptoms mirror mine so closely, Id recommend going straight for the proper diagnostic and repair rather than trying temporary fixes. Also worth noting, these cold start problems tend to gradually worsen if left unaddressed. In my case, the rough idle periods started lasting longer until I got it fixed.

Thanks for the detailed insights. Your experience matches what I'm dealing with so closely that I'm now pretty confident its a similar fuel injection issue. The flickering CEL and fuel consumption increase seem to be common symptoms of this problem. Considering that band-aid solutions like fuel system cleaners didnt work in your case, I think I'll skip those and go straight for the proper repair. The 580 Euro quote seems reasonable based on what others paid for similar work. Going to book it in next week for the fuel rail inspection and likely injector replacement. Rather fix it properly now than wait for it to get worse, especially since the cold start problems are already affecting my daily commute. Will update the thread once its fixed in case anyone else runs into similar hard starting and rough idle issues with their TFSI engine. Thanks again for helping me avoid wasting time and money on temporary solutions.