Rough Cold Starts? A5 Fuel Injector Issues Explained

I faced a very similar issue with my Audi A4 2.0T (2010). Based on some experience working on VAG engines, your symptoms sound exactly like what I encountered. The rough idle and cold start problems were classic signs of a failing fuel injector. Initially thought it might just need injector cleaning, but diagnostic tests revealed one injector was completely defective. The repair involved: Full fuel system diagnosis, Removal and testing of all injectors, Replacement of one faulty injector, Recalibration of the fuel delivery system Total cost was 515 Euro, which included parts and labor. The fix completely resolved the cold start problems and eliminated the rough idle. Before proceeding with repairs, could you share: Current mileage on your A5? Any check engine lights present? Have you noticed decreased fuel efficiency? Any misfires or stuttering when accelerating? This information would help determine if your issue is identical to what I experienced and whether you might need similar repairs. My workshop mentioned these issues are somewhat common on these engines, especially as they age. Regular fuel system maintenance and quality fuel can help prevent injector problems.

Thanks for the helpful information. My A5 has 124241 KM and just had its regular service last month where they changed oil and filters. No warning lights currently showing. Fuel efficiency has dropped about 15% in the last 2 months. When accelerating hard, there is a slight hesitation and occasional misfire, especially when the engine is still cold. The rough idle is most noticeable first thing in the morning. The symptoms you described match mine exactly. I was considering trying a fuel injector cleaning service first before full replacement. Do you think that could help, or should I go straight for injector replacement? The fuel rail and other fuel delivery components were checked during my last service and apparently looked fine.

Thanks for the additional details. Based on your symptoms and my experience, I would skip the injector cleaning service. When I had similar issues on my A5, the cleaning didnt resolve the underlying problem and I ended up paying twice, once for cleaning and then for the replacement anyway. The symptoms you describe, fuel efficiency drop, cold start misfires, and rough idle, are nearly identical to what I experienced. The fuel rail being fine is good news, as it narrows down the issue to the injectors themselves. Your mileage is very close to where mine was when the injector failed (I was at about 130000 KM). The fuel injection system on these engines typically starts showing these exact symptoms around this mileage point. Before replacing injectors, have your mechanic perform a fuel pressure test and injector balance test. This will confirm which injector is failing and ensure the fuel delivery system is operating at the correct pressure. In my case, these tests clearly showed one bad injector, making the diagnosis definitive. The repair cost should be similar to what I paid (515 Euro), assuming only one injector needs replacement. Make sure they use OEM parts, aftermarket injectors can cause more problems than they solve in these engines.

The comprehensive information you provided matches my situation perfectly. Based on your advice, I will skip the injector cleaning and go straight for proper diagnostic testing. The fuel pressure and injector balance tests sound like the right approach to pinpoint the exact problem. My symptoms do align closely with what you experienced, the engine misfire during cold starts, decreased fuel efficiency, and rough idle are identical issues. Given that my mileage is about where yours was when you had injector failure, it makes sense to address this now before it gets worse. I will contact my mechanic to schedule the diagnostic tests for the fuel injection system. The cost estimate of around 515 Euro seems reasonable, especially if it completely resolves these hard starting problems. I appreciate the tip about sticking with OEM parts, definitely not worth risking aftermarket components on the fuel system. Will proceed with the proper testing and likely injector replacement based on your experience. Thanks for helping me avoid the unnecessary step of injector cleaning that would have just cost extra money.