Ford Flex Knocking Combustion

Whoa, that sounds rough! I had similar issues with my Flex (don't remember the exact year), and it turned out to be something I hadn't even considered. You mentioned smoke, is it black, blue, or white-ish? Mine was blue-ish, which usually means oil is getting burned somewhere it shouldn't be. I'm no expert, but that's what happened to me. Did you check the error code stored? That might give you a better idea!

Thanks for the quick reply. The smoke is bluish. I know that often means oil consumption, which is concerning. I was focused on the combustion chamber. You mentioned checking the error code; which specific codes might be relevant?

Okay, so bluish smoke is a bad sign. As for the error codes, honestly, I can't remember exactly what mine were. It was a while ago. But I do remember my mechanic saying that bluish smoke and those particular codes together pointed towards a problem that was beyond my skills to fix myself. I'd strongly recommend taking your Flex to a trusted workshop. It's better to get it checked out properly before things get worse. It could save you money in the long run!

Thanks for the advice about the bluish smoke and going to a workshop. Based on your input and further checking, I took it to a mechanic. It turned out that deposits in the combustion chamber were the cause, like I thought. The mechanic cleaned it and adjusted the engine timing. The repair cost 425€. Thanks for sharing your experience; it really helped me figure things out.