AMG GT rough idle on cold start

Sounds familiar. I had something similar with my older AMG, though mine wasn't the GT model. Is it just during the cold start? The injectors have these tiny holes that spray the gasoline. If one of those holes gets clogged up with gunk, then the fuel doesn't spray right, and this can cause a rough idle and a misfire. When the engine warms up, the other injectors take over. That's why the problem goes away once the engine is warm. Have you checked if the engine light is on? Codes can help point to the specific cylinder that's having trouble.

Right, makes sense. Appreciate the info on the injector function. Regarding the engine light, yes, it did throw a code. Specifically, it indicated a misfire on cylinder 3. So, considering your experience and the code, are you leaning towards a specific injector issue on that cylinder? That would be the next step, right?

Yep, misfire on a specific cylinder definitely points to the injector. Though I am just a novice, going to a mechanic is probably the best choice. They can do more advanced injector tests and confirm if it's truly defective. It's a bit beyond my scope of knowledge, so I am unsure about how to proceed after that.

Understood. Thanks for sharing your insights. Took it to my mechanic, and after an injector test, cylinder 3 injector was indeed faulty. Replaced the cold start injector. Total cost 515€. Runs smooth as silk now, even on cold starts.