Seeking Advice for Multiple Issues with '09 Mazda Biante: Black Smoke, Check Engine Light, Power Loss, and Unstable Idling

Hey! I had a very similar issue with my '07 Mazda CX-7, also a Gasoline engine. So, I can safely say I have some experience dealing with this pesky problem. From my one- -garage, turns out it was the cable/plug on the idle control valve that was the culprit. Had to replace it as it was defective. It was running me in circles, but once identified and sorted, all those erratic behaviors stopped. Cost me about 155€ at my local workshop, but it was a crucial fix. However, in order to give you a more precise steer, would you be able to provide your mileage, maintenance history or any recent changes done on the car? Providing these information will be really helpful. Good luck, and I hope this helps you!

Hey, thanks for the info! The Biante's only got 14999 KM on it. As for recent changes, I haven't done anything too impactful apart from the regular service, which was done a couple of months ago. I will definitely check the cable/plug on the idle control valve. If it's as simple as that, it'll save me a lot of headache. Appreciate the help!

No worries, glad to help out! Given that your Biante has relatively low miles, it makes sense to first check out the less severe possibilities like then idle control valve plug before delving into more critical components. Besides the cable/plug, also inspect the valve itself - there could be carbon build-up that's causing the jerkiness and other symptoms. If you're comfortable doing some at-home mechanics, you might even be able to clean the valve yourself; it's not too complex. Remember, diagnosis is key here. Consider investing in an OBD reader and check to see what codes pop-up when the check engine light comes on; it can save you a ton of time and money down the road. Should your problems persist despite all these, it might be time to consult a professional workshop: it could indicate a deeply-rooted issue. Good luck, and don't hesitate to keep us posted about your progress! Cheers.

You're a lifesaver! I've got some basic tools and the guts to give it a shot, so I'll definitely inspect the valve for any carbon build-up and try cleaning it myself. If the issue's still there, I'll look into getting an OBD reader like you suggested - seems like a handy tool to have. And if I can't figure it out with all that, off to the professionals it is. I'll keep you all posted on how it works out. Cheers for the guidance, really appreciate it!