Q3's Cold Start Nightmare: Rough Idle & Misfires

Had similar cold start problems with a 2018 Q5 2.0T. The symptoms match exactly what you describe, hard starting, rough idle and misfires during cold operation. The fuel delivery system required attention after diagnostic testing revealed faulty injectors. An injector test showed inconsistent spray patterns and leakage. The main issue was carbon buildup restricting proper fuel atomization in cold conditions. This is definitely a serious problem that needs addressing. Faulty injectors can lead to poor fuel economy, increased emissions, and potential engine damage if left untreated. The repair involved: Complete fuel rail pressure testing, Individual injector flow rate measurement, Removal and ultrasonic cleaning of injectors, Replacement of 2 defective injectors, ECU adaptation after repair The improvement was immediate, instant cold starts, smooth idle, and no more morning misfires. Would strongly recommend getting a proper fuel system diagnosis from a shop with specialized diagnostic equipment. This isnt something that resolves itself and requires professional attention.

Thanks for sharing those details about the injector cleaning and testing. Your cold start problems sound exactly like what I experienced with my Audi Q3 last winter. A proper injector test revealed 3 problematic injectors causing those hard starting issues in the morning. The repair resolved all the engine misfire symptoms and rough running. Did the problems ever return after the fix? Also wondering what the total repair cost was for your fuel system work, if you dont mind sharing. Its helpful to know for others facing similar issues.

Great to hear you got those cold start problems resolved. Since having the faulty cold start injector replaced on my Q5, the hard starting issues never returned. The fuel delivery system has worked flawlessly for over 18000km now. The total repair cost was 515 Euro for diagnosing and replacing the defective injection valve. Money well spent considering how the rough idle and cold start problems completely disappeared. The fuel injection system now works exactly as designed, with instant starts even on cold mornings. One tip: regular fuel system maintenance and using quality fuel helps prevent carbon buildup that can affect injector performance. The improved fuel rail pressure and spray pattern after the repair made a noticeable difference in both cold and warm operation.

After months of frustrating cold start problems with my Q3, I finally got it properly diagnosed and fixed at a specialized shop. The fuel system diagnostic revealed multiple issues affecting fuel delivery during cold starts. Three faulty injectors were causing the hard starting and rough idle symptoms I was experiencing. The repair involved: Complete fuel injection system testing, Professional cleaning of all injectors, Replacing 3 defective injectors, Fuel rail pressure verification, Computer adaptation reset Total cost came to 780 Euro but worth every cent. The Q3 now starts instantly even on cold mornings with no more rough running or engine misfires during warmup. Really glad I got a proper diagnosis instead of continuing to guess at the problem. For anyone else dealing with similar cold start issues, dont wait too long to get it checked out. Proper fuel system testing makes all the difference in pinpointing the exact problem.