Seeking Advice on 2020 Mazda CX8 Diesel Emitting Black Smoke and Experiencing Power Loss - Potential Faulty Boost Pressure Sensor Issue?

Hey there, it sounds like you're having a real rough time with your Mazda. I gotta tell you, I'm not exactly a car guru, but I've had similar probs with my '18 Mazda CX5 Diesel. Just like your CX8, mine started puffing black smoke and shaking something fierce - scared the pants off me! Turned out it was a waste gate valve defect. My trusted local mechanic helped me out. To fix the issue, I ended up shelling out around €860, which hurt a little but you know, better safe than sorry. Anyway, could you provide a little more info about your car? Like have you done any recent mods, its mileage or better yet, any recent maintenance you might have had done? It's all about the little details. Happy to help further!

Hey! Thanks a bunch for your input. The details you've given drop quite a helpful light. No mods done recently except for some basic stereo upgrades, nothing that would mess with the engine. She's done a staggering 298147 km already, a bit old but gold, you know! As for the latest service, it was around 6 months ago at a certified Mazda shop. They didn't make any significant findings apart from usual stuff. I guess I'll try digging deeper into the waste gate valve defect. Cheers!

Hey back at ya! Good to hear you're taking care of your ride. With those miles, it's pretty impressive she's still running without giving you too much grief (touch wood)! I know what you mean by old but gold, they build them tough, these Mazdas. Alright, so everything seems pretty standard with no major changes - that's a start. To be honest, the symptoms you're seeing, especially the black smoke and drop in power, could indeed be down to a faulty boost pressure sensor - your initial gut feeling ain't off the mark. But then again, with the jerking on acceleration, the hissing sound and the stalling, it feels like there could be something more. And since I had a similar situation with my CX5, the waste gate valve still might be worth looking into. At the end of the day, it's hard to tell without getting under the hood. You could try plugging in an OBD2 scanner if you've got one, might give you some diagnostic codes to work with. Otherwise, might be a good idea to book another appointment with the Mazda or a local mechanic you trust. Let us know how it turns out. Drive safe!

Cheers for the clear and detailed explanation! You're a lifesaver. You're right, nothing beats a good professional look under the hood. I do indeed have an OBD2 scanner lying around somewhere, I'll give that a go over the weekend. Depending on what codes it throws out, I might have to book an appointment with my mechanic. Bummer about the expense but hey, gotta keep the beast running smoothly, aye. Will keep you posted on what I find out. Drive on and stay awesome!