Audi A8 Cold Start Misfire Fix: Bad Injector Issue

Having dealt with very similar cold start problems on my 2004 Audi A6 4.2L, I can share my experience. The symptoms were nearly identical, rough idle on cold starts and occasional engine misfires during the first few minutes. After multiple diagnostic attempts, my workshop identified a defective fuel injector that was causing inconsistent fuel delivery during cold starts. The repair involved: Complete diagnosis of the fuel system, Removal and testing of all injectors, Replacement of one faulty injector, Cleaning of the remaining injectors, System reset and adaptation Total cost was 515 Euro including parts and labor. Since the repair, the cold start problems completely disappeared and the engine runs smoothly from startup. Before suggesting this might be your exact issue, could you share: Any check engine lights or stored error codes? Does the rough idle occur only during cold starts or at other times too? Have you noticed any changes in fuel consumption? Are you experiencing any drop in power while driving? When was your last fuel system maintenance done? This information would help determine if your symptoms match my experience with the faulty injector or point to other potential causes.

Thanks for sharing your experience. My A8 has 26190 KM and was last serviced 3 months ago. The diagnostic scan revealed P0201 and P0204 codes. The rough idle is definitely more pronounced during cold starts, and fuel consumption has increased by about 15%. No significant power loss while driving. After reading your post, I had the fuel rail pressure tested. The mechanic found low pressure readings during cold starts. Further inspection showed two fuel injectors were indeed failing intermittently, causing the hard starting and rough idle symptoms. Getting the repair quote tomorrow, but based on your costs, I am at least prepared for what to expect. The fuel delivery issues match exactly what you described.

Thanks for the update on your A8. The P0201 and P0204 codes confirm my suspicions about injector problems, these are the same codes I got before my repair. Having two failing injectors explains the more severe fuel injection issues youre experiencing. The low fuel rail pressure during cold starts combined with the higher fuel consumption perfectly matches the symptoms I had. My repair costs might actually be on the low end since you need two injectors replaced rather than one. After my injector cleaning and replacement, I not only saw the rough idle and hard starting issues resolve, but my fuel consumption returned to normal. The engine misfire problems completely disappeared, especially during those critical first few minutes after startup. One tip: make sure they perform a thorough fuel system cleaning when replacing the injectors. In my case, debris from the failing injector had contaminated the fuel rail slightly, and cleaning it prevented any residual issues. Would be interested to hear what quote you get. From my experience, the repair, while not cheap, completely solved all cold start related problems.

The fuel injection issues you described match my situation perfectly. I just received the repair quote, 890 Euro for replacing both injectors, including a complete fuel system cleaning and diagnostic fees. This is higher than your repair cost, but makes sense since I need two injectors instead of one. The mechanic confirmed the injector test results show intermittent failure patterns during cold starts, explaining the engine misfire symptoms I was experiencing. They also recommended cleaning the entire fuel rail to prevent any contamination issues, just as you suggested. I have scheduled the repair for next week. The increasing fuel consumption and those persistent cold start problems really need to be addressed. Your feedback helped confirm I am making the right call on this repair, especially since your symptoms and diagnostic codes were so similar to mine. Will update once the work is completed to confirm if it resolves all the fuel delivery issues. Thanks again for sharing your experience, it really helped guide my decision making on this repair.