mikafischer5

SM3 Rough Running Misfires

My 2007 Renault SM3 with a gasoline engine is running terribly rough. The check engine light keeps popping on, and the whole car jerks violently when I try to accelerate. I suspect combustion misfires, but I'm not sure where to start. Could it be the fuel pump? Or something worse?

The 2007 Renault SM3 is experiencing rough running and misfires, with the check engine light frequently activating. The initial suspicion is combustion misfires, potentially due to a faulty fuel pump. However, another owner with similar issues suggests checking the fuel injectors, as these can cause rough idling and power loss. After professional diagnosis, a defective injector is confirmed as the cause, and replacing it resolves the problem.

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4 comment(s)

I've got an SM3 too. Had a similar issue last year. Check your injectors. Misfires and rough running sound like a fuel delivery problem. Have you had any issues with starting, or noticed any weird smells?

Injectors, you say? Hmm, I hadn't considered that. Could you elaborate a bit more? What exactly did you experience with your SM3 when the injectors were acting up? And did the check engine light show any specific error codes relating to the injectors?

The symptoms were pretty much identical to yours - rough idle, check engine light, loss of power. I scanned the codes and it pointed to cylinder misfires. I tried fuel additives and cleaning the throttle body, but nothing worked. Eventually took it to a workshop and they diagnosed a faulty injector. Best to get it checked out professionally.

It seems my problems are going to be more costly than I hoped, but at least I have a direction now. Just got the car back from the workshop. You were spot on – defective injector! The bill came to 515€, but at least the car runs smoothly again.

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RENAULT

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SM3