Renault Scenic Rough Cold Start

That sounds familiar. I had a similar issue with my old Opel Corsa. Different brand, but the symptoms were almost identical: hard starting and rough running when cold. I was convinced it was a fuel delivery problem. Did you check the simple things like the fuel filter? Is it clogged maybe?

Thanks for the quick response! I checked the fuel filter; it looked relatively clean. But you mentioned a fuel delivery problem on your Corsa. Was it the injector itself, or something else in the fuel system?

Well, in my case, after much head-scratching, it turned out to be a faulty injector. The mechanic said it was leaking when it shouldn't, flooding the engine on startup. Best to get it properly diagnosed, I think. A workshop visit will be inevitable.

For anyone interested: it was indeed a faulty cold start injector. They replaced it, and now the engine starts perfectly, even on the coldest mornings. Cost me around 515€, but it was worth it. Thanks for pointing me in the right direction!