Black Smoke & Boost Issues: Infiniti QX Diesel Help

Hey there, had exactly the same symptoms on my 2015 Infiniti QX50 diesel last summer. That whistling sound and black smoke usually points to a failing wastegate valve in the turbo system and that's exactly what it was in my case. Took it to the dealer after my local mechanic couldn't properly diagnose it. They confirmed the wastegate was stuck partially closed, causing irregular boost pressure. This explained the power loss and rough running. They had to replace the entire wastegate assembly and recalibrate the ECU. It was quite a serious job that took them two days to complete, but it fixed all the issues no more smoke, whistling, or shaking. The car's been running smooth ever since. If you're getting these symptoms, I'd strongly suggest going straight to an Infiniti dealer or a specialist who really knows their turbo systems. This isn't something you want a general mechanic messing with. Hope this helps!

Thanks for sharing your experience! This definitely sounds similar to what I'm dealing with. I'll probably take your advice and head to the dealer. Quick question do you remember roughly how much the repair set you back? Also, has everything been running smoothly since then, or have you noticed any other issues pop up?

Hey again! Yeah, happy to help! So after seeing the mechanic, they fixed the Malfunction in the boost pressure system total bill came to 860€ for the wastegate valve replacement. I know it's not cheap, but honestly, it was worth every penny because my QX50 has been running like a dream since then. No other issues at all the black smoke disappeared completely, that annoying whistling sound is gone, and the engine's running super smooth now. It's like having a completely different car! The power's back to normal too, which is such a relief. The dealer did a really thorough job, and I'm glad I went with them instead of trying to save a few bucks at a regular shop. Sometimes you just need the specialists who know these cars inside and out, you know? Let me know how it goes if you decide to get it fixed. Always curious to hear if others have the same experience!

Update on my Infiniti situation! Finally took it to the dealer last week, and you were spot on! It was exactly what you said a faulty wastegate valve. Cost me around 900€, which was a bit of a punch to the wallet, but honestly, it was totally worth it. The difference is like night and day! No more black smoke, that annoying whistling is gone, and the engine's running super smooth now. Should've just gone to the dealer straight away instead of stressing about it. They even gave the car a full inspection while it was there and everything else checked out fine. Really appreciate your advice saved me from probably making things worse by going to another unusual mechanic. Sometimes you just have to bite the bullet and pay a bit more for someone who knows what they're doing, right? Thanks again for pointing me in the right direction! Car's running like new now, and I couldn't be happier with how it turned out.