williblitz1

Mercedes SL reduced engine power issue

My 2009 Mercedes SL Gasoline engine is acting up. I'm getting reduced engine power, the check engine light is on, rough running, jerking acceleration, and it sometimes stalls at idle. Seems like a mixture preparation error. Could it be the injectors?

4 comment(s)

Sounds familiar. I had a similar issue with my SL, though I can't recall the year. Those symptoms point to an air-fuel ratio problem, possibly running a rich mixture. Have you checked your spark plugs? Sometimes a faulty mass airflow sensor or a dirty throttle body can also cause similar issues, like throwing off the air-fuel ratio. It's like a domino effect, one thing goes wrong and the rest follows.

Spark plugs are new. How can I check the mass airflow sensor or throttle body? What exactly did you have to replace to fix your car?

Well, without proper diagnostic tools, checking the mass airflow sensor is difficult. A mechanic can read the values. As for the throttle body, you can visually inspect it for carbon buildup. In my case, it turned out to be a defective injector. It was causing a rich mixture. You really need to get a diagnostic scan to pinpoint which one is failing. Best get it to a workshop.

Thanks for the insight. Took it to the workshop, and you were right - a defective injector. Replaced it and it cost me 515€. Runs like new now.

Join the discussion now: