Black Smoke & Power Loss in QX: Lambda Sensor Alert

Hey there, had nearly identical issues with my 2016 Infiniti QX70d (diesel) last summer. The symptoms you're describing sound exactly like what I experienced power loss, rough idle, black smoke, and terrible fuel economy. Initially thought it was the Lambda sensor too, but it turned out to be a cracked exhaust manifold and a failing turbo. Took it to my regular shop they found multiple exhaust leaks at the manifold-to-turbo connection. These leaks were messing with the sensor readings and causing the engine to run rich. The turbo was also damaged due to the exhaust leak. Had to get the manifold replaced and a turbo rebuild. It was definitely a serious issue that needed immediate attention running like that can damage other engine components. The repair wasn't quick, but my car's been running like new since then. Just make sure to find a shop that specializes in Infiniti diesels. These symptoms could indicate several different issues, and you'll want someone who knows what they're looking at. Best of luck!

Thanks so much for sharing your experience! That's really helpful. I've booked it in with a specialist Infiniti shop next week sounds like I made the right call not ignoring it. Just curious, do you remember roughly how much the repairs set you back? And has everything been running smoothly since the fix, or have you had any other issues pop up?

Hey again! Just wanted to update you my situation actually turned out better than expected! While I initially had those major repairs last summer, I recently took it back to the shop for the Lambda sensor issue, and that's all sorted now. The exhaust leak repair cost me €265.00, which wasn't as painful as I'd feared. The car's running like a dream now way better fuel economy, no more black smoke, and the power's back to normal. Haven't had any other issues pop up since the fixes. I can actually enjoy driving it again without worrying about every little noise or problem! I think you're making the right move taking it to an Infiniti specialist. They'll be able to pinpoint exactly what's going on. Hope your repair bill turns out to be on the lighter side too! Let us know how it goes always good to share experiences and help others in the community. Keep us posted!

Hey, thanks for the follow-up! Just wanted to close this thread and share what happened. Finally got my car back from the shop yesterday. You were right about going to the Infiniti specialist they diagnosed it quickly and found it was actually a combination of issues. Had a faulty turbo sensor and some clogged fuel injectors. Total bill came to 780€, which included parts and labor. Not cheap, but definitely better than I expected considering the symptoms. They cleaned out the entire fuel system and replaced the sensor. Car's running amazingly now no more black smoke, got my power back, and fuel consumption is back to normal. What a relief to have it sorted! Really appreciate everyone's input here, especially your detailed experience it helped me make the right decision about getting it checked out properly instead of putting it off. Lesson learned: don't wait when these symptoms show up! Thanks again for all the help! Case closed!