Q7 Cold Start Issues: Bad Injector May Be The Culprit

I had a very similar issue with my 2009 Audi Q5 last winter. As someone with some experience working on VAG engines, I initially thought it might be something simple like bad fuel quality. The symptoms matched yours exactly, cold start problems and engine misfire during the initial startup phase. After attempting basic solutions like fuel system cleaner additives, the issues persisted. When I took it to my regular workshop, they performed a comprehensive injector test on all cylinders. The diagnostic showed one injector was failing intermittently during cold starts, affecting the fuel injection sequence. They confirmed this by testing the electrical signals and spray patterns. The fix required replacing the faulty injector, which came to 515 Euro including parts and labor. Since the repair, the cold start issues disappeared completely and the engine runs smoothly from startup. Before suggesting specific solutions for your Q7, could you share: Current mileage, Type of fuel you typically use, Whether any check engine lights are active, If the problem gets better once the engine warms up, Any recent fuel system maintenance history This information would help determine if your case is similar to what I experienced with my Q5.

Thanks for sharing your experience. My Q7 just hit 104505 KM and had its last service 3 months ago. The symptoms match what you described perfectly. The rough idle and engine misfire issues completely disappear once the engine reaches operating temperature. No check engine light has appeared yet. Your input about the injector test is particularly helpful. The fuel injection diagnosis approach your mechanic took sounds thorough. Since my car exhibits exactly the same cold start problems, I will request a similar injector test procedure. The cost estimate gives me a good baseline for what to expect. I typically use premium grade fuel, but the engine misfire pattern remains consistent regardless of fuel quality. Sounds like a proper fuel system inspection and injector testing is the next logical step.

Thanks for the follow-up about your Q7. Based on your mileage and symptoms, this definitely mirrors what I experienced. The fact that your engine misfire and rough idle clear up after warm-up strongly points to injection system issues, just like my case. Since we both drive similar generation Audi engines, I should mention that after my injector replacement, I also had the workshop perform a complete fuel injection system cleaning. This preventive step helped ensure the remaining injectors wouldn't develop similar issues. The hard starting in cold conditions combined with normal operation at operating temperature is a classic sign of injector problems in these engines. Given your recent service history and premium fuel usage, I doubt fuel quality or maintenance gaps are contributing factors. One thing I learned through my repair process: the diagnostic equipment specifically designed for VAG fuel injection systems was crucial for pinpointing the exact injector causing the cold start problems. Make sure your workshop has this capability. Total cost for my complete service including injector replacement and system cleaning was around 650 Euro. Prices may have changed since then, but it gives you a rough reference point.

Thanks for all the detailed feedback. Given the matching symptoms and similar vehicle type, I feel more confident about the direction to take. The fuel injection diagnosis path sounds exactly like what my Q7 needs. I will schedule an appointment and specifically request the fuel system diagnostic testing, focusing on cold start performance and injector spray patterns. Good point about making sure they have the right diagnostic equipment for testing VAG engines. My recent service and consistent premium fuel use rules out maintenance problems, so investigating the fuel delivery components directly makes sense. Since my symptoms match your experience so closely, especially how the hard starting and rough idle clear up after warm-up, I expect to find similar injection system issues. The cost estimates you provided for both the injector replacement and complete fuel system cleaning help set realistic expectations. Will request both services if they find a faulty injector, since preventive cleaning of the remaining injectors seems wise at this mileage. Will update once I get the diagnostic results and repair completed. The fuel rail inspection and injection system testing should reveal if I have the same underlying problem you encountered.