BMW XM Cold Start Nightmare: Rough Idle and Hard Starts

Hey there! I had a similar issue with my 2020 BMW X6 M (had some experience working on BMWs). The symptoms you're describing sound exactly like what I dealt with about 6 months ago. Multiple start attempts, rough idling, and terrible fuel consumption when cold, classic injector problems. Took it to my trusted workshop and they diagnosed a faulty injector. Had to replace it, set me back about 515 Euro, but it fixed the issue completely. Haven't had any problems since then. Before I can provide more specific advice, could you share: How many miles/kilometers are on your XM? Are you getting any check engine lights? Does the rough running smooth out once the engine warms up? My mechanic mentioned these problems are somewhat common in the M series engines. If you're experiencing similar symptoms, I'd recommend getting it checked soon to avoid potential damage to other components.

Thanks for the detailed response! Currently at 114606 KM and just had my service last month. Yeah, the rough running does smooth out after warming up, and surprisingly no check engine light so far. I'm definitely gonna have it checked out soon, don't want to risk any further damage. Really appreciate you sharing your experience with the injector replacement. Good to know what I might be looking at cost-wise if it turns out to be the same issue.

Hey again! Glad I could help earlier. You know, after reading about your mileage and symptoms, I'm even more convinced we had the same issue. My X6 M was actually around 110000 KM when I faced these problems. The fact that it smooths out after warming up is exactly what happened with mine. And interestingly, I didn't get any check engine light either, which initially made me think it wasn't serious. But my mechanic later explained that sometimes these issues won't trigger the light until they get really bad. Just to add to my earlier response, after the injector replacement, I noticed my cold start fuel consumption dropped significantly. Used to burn through about 20% more fuel during those first few minutes, but now it's back to normal. Quick tip from my experience, when you take it in, ask them to check the fuel pressure regulator too. My mechanic did that while he was in there, and turns out it needed a small adjustment. Didn't cost much extra but helped with overall performance. Keep us posted on what you find out. Always interested to hear how these issues turn out, especially with similar models.

Thanks again for the follow-up! That's super helpful about the fuel pressure regulator, I'll definitely mention that when I take it in. It's actually reassuring to hear someone had such a similar experience, especially with the mileage being so close. I just scheduled an appointment for next week, so I'll make sure they do a thorough check of both the injector and the regulator. The fuel consumption thing really hits home, I've been burning through way more fuel than usual during those cold starts. Really hoping it's just the injector like yours was. I'll update once I get it checked out and let you know what they find. Really appreciate all the detailed advice!