BMW X3 Cold Start Issues: Rough Engine & High Fuel Use

Had the same issue with my 2015 BMW X4 last winter. The symptoms matched yours exactly, rough idle when cold, delayed starts, and terrible fuel economy during warm-up. Turned out two fuel injectors were failing. Got it checked at a garage and diagnostic tests confirmed injector issues. The repair involved replacing both defective injectors and cleaning the remaining ones. It was a serious job since they had to remove quite a bit to access the injectors properly. The car needed to stay at the garage for two days. The difference after fixing was night and day, starts immediately now, smooth idle from cold, and fuel consumption is back to normal. If you're experiencing these symptoms, don't wait too long. Faulty injectors can cause more engine damage if left unchecked. Make sure to get a proper diagnosis with specialized equipment first though, since similar symptoms can come from other issues too.

Thanks for sharing that, it's really helpful! Sounds exactly like what I'm experiencing with my X3. I'm actually relieved to hear it was "just" the injectors in your case and not something worse. By the way, do you remember roughly how much you ended up paying for the whole repair? Also, has everything stayed running smoothly since the fix, or have you noticed any other issues pop up?

Hey there again! Yeah, I'm happy to share the costs, I paid 515 € for fixing the faulty cold start injector, and honestly, it was worth every penny. The mechanic really knew what they were doing, and they sorted it out properly. Since getting it fixed, my X4's been running like a dream, starts up instantly every morning with no hesitation, and that annoying rough idle is completely gone. Fuel consumption is back to what it should be too. It's been several months now, and I haven't had a single issue pop up related to the injection system. Trust me, getting it fixed sooner rather than later was definitely the right call. The mechanic mentioned that leaving it too long could've caused more expensive problems down the line. If your symptoms are matching what I had, I'd say go ahead and get it checked out. Just make sure you find a good mechanic who really knows their way around BMWs, it makes all the difference. Let me know how you get on with yours. Always happy to help another BMW owner out!

Thanks for all the detailed info! I actually just got back from the mechanic today. You were spot on about the injectors! Took your advice and found a really good BMW specialist, they ran diagnostics and found two bad injectors, just like in your case. The repair cost me a bit more, around 650, but they did a thorough job. They cleaned the whole system and replaced both faulty injectors. Took them about a day and a half to complete everything. Just drove it home and wow, what a difference! The engine starts right up now, idles perfectly smooth, and that annoying rough running is completely gone. Should've done this weeks ago instead of worrying about it. Really appreciate you sharing your experience. It helped me make the decision to get it fixed properly instead of trying cheaper alternatives. Money well spent for sure!