I have a 07 Mazda 3 and it seems like ita getting worst by the day. I have a check engine light on with the code P2177 System too lean, I'm pretty sure its losing its power when accelerating. I'll be honest, I don't really know what a misfire is like, but I'm pretty sure it may be as the engine is running rough at the moment.

My biggest worry is the sound of the engine when putting my foot down on the gas. It seems to get worst and louder every day. The best way I can explain it, is that it sound like a rattle in the engine. I do have a video, it's the only one I could get. Please watch it.

Is this possible that the spark plugs need replacing? I have no idea what they were last changed.

Video: Video

It doesn't seem that loud, but it really is

  • Check for vacuum leaks at the intake manifold.
    – Moab
    Apr 20, 2020 at 19:30

1 Answer 1


System too lean often means you have a fuel delivery problem like clogged injectors or a bad fuel pump. One easy and cheap culprit is often the fuel filter, a filter that's getting clogged can let enough fuel to idle properly, but then won't let enough through for higher revs. I'd start with that as the part should be less than $20 and you can do it yourself if you are inclined. If that doesn't solve it a fuel pressure test would be the next step.

  • If it was a fuel delivery problem, would that cause the engine to sound that that when accelerating?
    – Jonathon
    Apr 20, 2020 at 14:39
  • I haven't listened, but engines that are misfiring can be very noisy. You could have detonation, which is very bad for your engine.
    – GdD
    Apr 20, 2020 at 14:43
  • @Jonathon - A lean misfire is very bad juju for the engine. It's not something you want force on your engine. I haven't listened to the video yet either, but from your description a lean misfire is exactly what's going on. GdD is spot on with trying to replace the fuel filter first. I don't see a fuel filter offered individually, so it may be a part of the fuel pump assembly. Apr 20, 2020 at 16:16
  • It's really strange because the sou d doeant happen all the time. It happens randomly. I guess I'll check the filter first. I appreciate your help guys
    – Jonathon
    Apr 24, 2020 at 21:43

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