alina_flame6

SM3 Cold Start Problems

Hey, I'm having trouble with my 2012 Renault SM3, gasoline engine. It's done 105594 km. Lately, it's been starting terribly when it's cold. The engine runs super rough in the initial start-up phase, like it's misfiring or something, and it generally starts poorly. I suspect a faulty cold start injector but I'm no expert. Any ideas? Has anyone had similar cold start problems?

4 comment(s)

I have an SM3 too, and I had similar symptoms a while back. Poor engine running in the cold start phase and hard starting definitely sounds like it could be fuel related. Have you tried testing your injectors? A defective injection valve/injector can cause these issues, leading to rough idle and engine misfires, especially when the engine is cold.

Thanks for the quick reply! How did you go about testing your injectors? Is that something I can do myself, or am I better off taking it to a mechanic? I'm not completely clueless, but I don't want to mess anything up even more. Any advice on whether it is worth it to go to the workshop right away?

Testing injectors can be tricky without the right tools. You could try using a multimeter to check the resistance, but that won't tell you if they're spraying correctly. Honestly, considering the symptoms, it's probably best to get it checked by a workshop. I ended up needing a new injector, and the whole job, including diagnostics, was around 515€. It's not cheap, but it solved the problem completely.

Thanks so much for the info! I think you're right, I'll book it in with a mechanic to get the injectors properly tested. Hopefully, it's just one injector that's gone bad. Appreciate the help!

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