Discovery V8 Running Rough: Cold Start and Black Smoke Issues

Hey there! I had a pretty similar issue with my '02 Range Rover 4.4 V8. As someone with some experience working on cars (mostly basic maintenance and troubleshooting), those symptoms sound exactly like what I dealt with last year. Mine started with rough running and black smoke, then got worse until it was a real pain to start. Turned out one of the injectors was definitely shot. Took it to my regular workshop, and they diagnosed it using their diagnostic tools. The mechanic showed me how the faulty injector wasn't spraying properly, which explained all those symptoms you're describing. Had it fixed for about 515 Euro, not cheap, but it transformed the car back to running smoothly. No more black smoke or starting issues since then. Before I can share more specific advice, what's your engine's mileage? And have you noticed any specific pattern when the stalling occurs (like only when the engine's cold or hot)?

Thanks for sharing your experience! My Disco has 99234 KM and just had its service last month. The stalling mostly happens when I'm idling at traffic lights or slowing down. It's definitely getting worse and sounds similar to what you experienced with your Rangie. Good to know about the injector being the culprit in your case, I'll get that checked out. Did your mechanic need to replace just the one injector or did they recommend doing a full set?

Hey again! Yeah, seeing your mileage and hearing about when it stalls, it's even more similar to what I went through with my Rangie. When my mechanic diagnosed it, he initially found one bad injector, but strongly recommended replacing the whole set. I was a bit hesitant about the cost at first, but he explained that when one injector fails at this mileage, the others usually aren't far behind. I ended up going with his advice and replaced all of them, definitely the right call in hindsight! The car's been running like a dream for the past year. The full set cost more upfront (around 1200 Euro), but saved me from potentially having to do the job again in a few months if another one failed. Quick tip from my experience, while they're doing the injectors, get them to clean the fuel rail and check the fuel pressure regulator too. Mine had some gunk built up that wasn't helping matters. Let me know what you find out when you get it checked. If you need any more specific details about what they did with mine, just give me a shout!

Thanks so much for the detailed advice! That's really helpful about replacing the full set, makes total sense to do it all at once rather than dealing with them failing one by one. I'll definitely get the fuel rail cleaning done too while they're at it. Just booked it in with my mechanic for next week, and I'll make sure to mention everything you've suggested. Really appreciate you sharing your experience, it's given me a much clearer idea of what I'm dealing with and probably saved me some back-and-forth with the workshop. I'll update you once it's sorted. Fingers crossed it'll be running as smoothly as your Rangie soon! Thanks again for all your help!