BMW 8 Series Running Rich, Symptoms and Solutions

Hi there! I have some experience working on BMWs. I actually faced almost the exact same issue with my 2016 BMW 7 Series last year. Total nightmare with rough running and excessive fuel consumption. Turned out one of the injectors was faulty, causing the engine to run super rich. Got it diagnosed at my regular workshop and they found fuel spray pattern was completely off. Had to replace the injector, cost me around 515 Euro but it fixed the problem completely. Those symptoms you're describing are textbook injector issues, especially the power loss and jerking during acceleration. Before you take it in though, could you share: Current mileage? Any recent maintenance done? Does it run worse when cold or hot? If it's similar to what I dealt with on my 7 Series, you'll want to get it checked soon to avoid damaging your catalytic converter from all that excess fuel.

Hey, thanks for sharing your experience! My 8 Series has 41227 KM and just had its service last month. The issue seems worse when the engine is cold, especially during morning starts. The symptoms you described with your car sound exactly like what I'm experiencing. Really helpful to know about the injector being the culprit in your case, it makes sense given how mine's acting up. I'll definitely get it checked out asap before it causes more problems. Did you notice any particular warning signs before your injector completely failed?

Hey again! Glad I could help with my previous experience. Yeah, with my BMW 7 Series, I actually noticed a few warning signs before the injector completely gave up. The first thing I noticed was this subtle ticking noise during cold starts, which I initially ignored (big mistake). Then the car started having this slight hesitation when accelerating from a stop, kind of like a mini-stutter. It wasn't too obvious at first, but it got progressively worse over about two weeks. The fact that your symptoms are worse during cold starts is really similar to what I experienced. Mine would sort of smooth out once warm, but those first 5-10 minutes were pretty rough. With your mileage being similar to what mine was when it happened (I was around 45000 KM), it's quite possibly the same issue. Just a heads up, when I waited too long to get it fixed, I started getting this strong fuel smell in the exhaust. That's when I knew I really had to get it sorted. Thankfully, no permanent damage was done, but my mechanic said I was cutting it close with the catalytic converter. If you're hearing any unusual ticking or smell fuel more than usual, I'd suggest getting it to the shop sooner rather than later. Better safe than sorry with these engines!

Thanks so much for those details! That's super helpful, especially about the ticking noise and fuel smell, I've actually started noticing a slight fuel odor lately but wasn't sure if it was related. I'm definitely not going to make the same mistake of waiting too long. I've already called my mechanic and booked it in for tomorrow morning. Really appreciate you taking the time to share your experience, it's given me a much better idea of what I'm dealing with. Sounds like I'm catching it early enough to avoid any serious damage to the catalytic converter. Will probably cost me a bit for the injector replacement, but better than having to deal with bigger problems down the line. Thanks again for all your help!