Black Smoke & Stalling: Infiniti M's Fuel System Crisis

Hey there! I had a similar situation with my 2014 Infiniti Q50 diesel last year (also known for these issues). Your symptoms sound exactly like what I experienced after changing my fuel filter black smoke, rough idle, and terrible fuel economy. In my case, it turned out to be air in the fuel lines and a faulty fuel pressure sensor. The dealership had to bleed the fuel system and replace the sensor. They also found that the high-pressure fuel pump needed recalibration. It wasn't a major repair, but it definitely needed professional attention because of the complex fuel injection system these diesels have. The black smoke usually points to either too much fuel or not enough air in the mixture. Since you're getting poor economy too, I'd bet it's related to the fuel delivery system. These Infiniti diesels are sensitive to fuel system issues. Got it fixed at an Infiniti specialist shop, and it's been running perfectly since then. Definitely recommend finding a mechanic who specifically knows these engines they're quite different from regular diesels. Hope this helps point you in the right direction!

Thanks for sharing your experience! That definitely sounds similar to what I'm dealing with. I'm relieved to hear it wasn't anything catastrophic. Can you remember roughly how much you ended up paying for the whole fix? Also, has everything been running smoothly since then, or have you noticed any other quirks pop up?

Hey again! Happy to give you an update. Since my last post, everything's been running like a dream with my Q50. After seeing the mechanic, they found and fixed the fuel injection pressure issue that was deviating from standard values. The whole thing, including fixing the error entry after the fuel filter change, only set me back 45€, which was a relief! I haven't had a single problem since the fix no more black smoke, engine runs smooth as silk, and my fuel economy is back to normal. It's amazing what a proper diagnosis and fix can do! These Infinitis can be a bit finicky with their fuel systems, but once you get them sorted, they're fantastic cars. If you're still looking for a mechanic, I'd be happy to recommend the specialist who worked on mine. They really know their stuff when it comes to these engines, and their prices are fair too. Just let me know if you want their details!

Thanks a lot for the detailed feedback! I actually took your advice and went to get it checked out yesterday. You were spot on it was indeed a fuel system issue. The mechanic I found specialized in Infinitis, and he diagnosed a faulty fuel pressure sensor and some air in the lines, just like your case. The whole repair came to about €500, including parts and labor. A bit more than yours, but they also had to replace a worn-out fuel line they discovered during inspection. Got to say, the difference is like night and day! No more black smoke, engine's purring again, and I filled up today already seeing better fuel economy. Really appreciate you sharing your experience it helped me make the right decision instead of putting it off and potentially causing more damage. The car's running great now, and I've finally found a mechanic I can trust. Thanks again for pointing me in the right direction! Best,