BMW 7 Diesel Cold Start Issues, Injector Problems?

Hey there! Car enthusiast with some experience here. I actually faced something very similar with my '01 BMW 5 series diesel last winter. Had almost identical symptoms to what you're describing. After struggling with rough starts and increased fuel consumption, I took it to my trusted workshop. They diagnosed a faulty injector, it wasn't atomizing the fuel properly during cold starts. The fix wasn't cheap (paid 515 Euro), but it solved all those issues completely. They had to replace the defective injection valve. The 5 and 7 series share similar injection systems, so it could be the same problem. Before I can help more specifically, could you tell me if you're getting any warning lights? Also, does it produce any unusual smoke during these cold starts? These details would help confirm if you're dealing with the same issue I had. The other thing worth checking is if it's all BMWs from that period, my mechanic mentioned the 3 series diesels sometimes had similar problems too.

Thanks for sharing your experience! Currently at 178681 KM and had my last service about 2 months ago. Actually, I do get a bit of white smoke during cold starts, but no warning lights on the dash yet. The rough running typically lasts about 2-3 minutes, then everything smooths out. Really appreciate the heads up about the repair costs, helps me budget for what might be coming. Think I'll get it checked out soon before it potentially gets worse. Did your car also have that slight shaking during the first few minutes after starting up?

Hey again! Thanks for those extra details about your 7 series. Yeah, that white smoke and shaking during the first few minutes is exactly what I experienced with my 5 series! Mine was at about 165000 KM when the issues started. The shaking was particularly noticeable when the engine was cold, it would vibrate for those first 2-3 minutes until it warmed up, just like yours. Just to add to my previous response, after I got the injector replaced, not only did the cold start issues disappear, but I noticed my fuel economy improved by about 15%. The white smoke completely vanished too. It's definitely worth getting it sorted sooner rather than later, I waited a bit too long and probably wasted quite a bit of fuel in the process. Quick tip: when I first noticed these symptoms, I tried using a fuel system cleaner additive. It helped slightly for about a week, but the problems came back. Don't waste your money on additives like I did, it's definitely an injector issue that needs proper fixing. Keep us posted on what you find out at the workshop. The symptoms are so similar to what I dealt with, I'd bet you're looking at the same repair.

Thanks so much for all this information, especially about the similar experience with your 5 series. The matching symptoms, white smoke, shaking, and that 2-3 minute warm-up period, really help confirm what I might be dealing with. Good to know about the fuel system cleaner too, was actually considering trying that first, but you've saved me from wasting money there. I've booked the car in for next week, and I'm feeling more confident now about what to expect. Really helpful to know about that 15% fuel economy improvement you got after fixing it, makes the repair cost easier to swallow knowing there's a silver lining. Will definitely update once I get the diagnosis. Thanks again for taking the time to share your experience, it's exactly the kind of real-world feedback I was hoping for when I posted this question!