Seeking Advice on Diagnosing and Fixing Issues with a 2009 Mazda Premacy Diesel - Black Smoke, Drop in Power, and Engine Noise

Hey, thanks a ton for your valuable input. Sounds pretty close to what I'm dealing with. My Premacy's clocked about 300,381 KM so far. The only service it's had apart from regular oil changes and maintenance was about 2 years back: had a coolant leak and had to replace some hoses and the radiator cap. Aside from the hissing and the whistle, there's this low grumble when it idles, kinda hard to explain. No other warning signs as of now – just hoping it's not too serious. I'll look into the waste gate valve situation, cheers!

Hey there, again. That mileage is actually impressive for a '09 Mazda. The low grumble at idle, combined with the other symptoms, doesn't sway away from my initial thought about the waste gate valve. It could be that the defect is causing the turbocharger to overwork or underwork making the engine behave in such an erratic way. Given this situation, I'd strongly recommend getting it checked out sooner rather than later. If left untreated, the issue could cause greater damage to your turbocharger and engine, leading to even costlier repairs. If it is indeed the waste gate valve, the hefty repair cost I mentioned before unfortunately is the rough ballpark. Remember to test drive it after the repair is done, just to ensure that all your symptoms are addressed. Good luck hope this mess gets sorted out soon! Staying optimistic here, cheers!

Hey again and thanks for your thoughtful advice. I guess it has been a good run with the old Premacy. I'll take your word for it and get it down to a workshop sooner rather than later to check out this waste gate valve. I'm aware repairs could hit the pocket, but fingers crossed, it'll still beat an engine replacement! Definitely won't forget that test drive - the smoother the better is what I always say. Again, really appreciate your help and fingers crossed, ey? Cheers!

Hello,I’ve plugged my car in and I’ve got the codes p0234 and p0236 one is turbocharger under boost and one is turbocharger over boost does anyone have any ideas to what it could be

Also I forgot to mention,every now and then doesn’t matter where you are in the rev range just coming into boost or already in boost just now and then it’ll stutter and then clear itself up and be perfectly normal,I haven’t seen any black smoke out the back and the only loss of power is when it’s stuttering after that it’s fine

The codes P0234 and P0236 indicate an issue with the turbocharger or supercharger boost system. The stuttering you're experiencing could be due to the engine not receiving the correct amount of air for the amount of fuel being used. This could be caused by a variety of issues such as a faulty boost pressure sensor, a leak in the boost pressure system, or a malfunctioning waste gate. I would suggest starting with the easiest check: inspect the hoses and connections in the boost pressure system for any visible signs of damage or leaks. If everything looks fine, you might want to consider having a mechanic inspect the boost pressure sensor and the waste gate. Remember, if the issue is left untreated, it could lead to more serious engine damage. Please keep us updated on your progress. Do you have any other questions?