QX Diesel: Hissing, Shaking & Power Loss What's Wrong?

I had almost identical symptoms with my 2015 Infiniti Q50 diesel last summer at 225k km. The hissing and power loss were spot on turned out to be a cracked intake hose where it connects to the intercooler. The rubber had deteriorated and split. Took it to my regular mechanic, and they pressure tested the intake system to confirm the leak. They had to replace the intake hose assembly and a couple of clamps. While they were at it, they checked all the other intake connections since these issues often come in pairs. It wasn't a super serious repair, but definitely not something you want to ignore. Running with a leaky intake can mess with your air-fuel ratio and potentially cause bigger problems down the line. The whole job took about 2-3 hours. The shaking at idle you mentioned sounds exactly like what I experienced it all cleared up after the fix. Make sure whoever checks it out does a proper pressure test of the intake system. Hope this helps.

Thanks for sharing your experience! That sounds exactly like what I'm dealing with. Do you remember roughly how much the repair set you back? And has everything been running smoothly since, or have you had any other issues pop up? Just trying to get an idea of what I'm in for with my QX.

Hey there! Happy to give you an update. After getting my Q50 fixed last summer, it's been running like a dream no more hissing, shaking, or power issues. The total bill came to 100€ for fixing the leaky intake hose, which honestly wasn't as bad as I'd feared. The mechanic found the crack exactly where the hose meets the intercooler, just like they suspected. Since getting it sorted, my car's been performing perfectly smooth idle, proper acceleration, no more weird noises. It's such a relief! The pressure test they did really helped pinpoint the exact problem, and I'm glad I got it fixed when I did. These kinds of issues can definitely snowball if you leave them too long. I'd definitely recommend getting yours checked out soon. The symptoms you're describing are spot-on with what I experienced, and it's better to tackle it now before it possibly leads to bigger problems. Plus, it's a relatively straightforward fix once they know what they're dealing with. Let me know how it goes with yours!

Thanks so much for all the info! I actually just got back from the mechanic today. You were spot on it was indeed a cracked intake hose! They found it pretty quickly with the pressure test, just like in your case. The fix was really similar to what you described, and my bill came to about 120€ a bit more than yours but still reasonable. They replaced the hose and checked all the connections, just to be safe. Took about 2.5 hours total. The difference in how the car runs now is like night and day! No more hissing, the idle is smooth, and the power's back to normal. Such a relief that it wasn't anything more serious. The mechanic was great too really took the time to explain everything and show me where the problem was. Really appreciate you sharing your experience it helped me know what to expect and gave me confidence that I wasn't dealing with something super major. My QX is purring like a kitten now! Thanks again for your help!