Fixing up my turbo cx7 and proper fueling

[Goscx7]

Hey guys. Let me introduce myself and my car to you all since it's my first post. I own a 2009 Mazda CX7 ER Series 1 2.3 MZR DISI TURBO. It's the 1 of only 2 in The Fiji Islands. I had it privately imported here last year in November. It was fine uptil February when it has a misfire and my Check engine light came on. I took it to the only Mazda dealer in fiju, and they got no idea about the engjne mt car has, but they worked on it. Anyways, They diagnosed my car, I don't remember the code but it was something like network error or something. And they said it was solved. So I had another check engine light, the car jerked hard when it happened and than the light went off in a couple of days. Than I found out the mazda dealer put 15w 40 oil and spark plugs with too much gap in it. So I resolved that issue. But my car still doesn't perform as well as it should, it's running very rich (I can smell it) and it drinks too much fuel 21L per 100 km or 12mpg. Also I'm filling it with regular 91 octane because down here in fiji Thats the only fuel we get.

Go guys I'd really like some advice on how to get my car to run normally in tip top condition again.

And also I want to modify it and get more power out of it. I'm not sure of where I should start though. And I wanna make more power on 91 octane

[Bingo]

I won't claim to be too knowledgeable about this sort of thing, but if now the only problems you're have are the MPG and occasional jerking (phrasing?), then my first thought is an O2 sensor and/or improperly gapped plugs (additionally I'm not sure what affect having 15w40 would have on it). Again, don't take my word for it, that's just my hunch. My main reason for typing this is to urge you not to mod it. It sounds like fun, but especially without a tuning device (for now at least) diagnosing problems will probably never end. Not to mention the shipping costs and time it would take to import parts that will inevitably need replacing if you go this route. This combined with the lack of backup support (a decent Mazda dealer) will lead to far more sorrow than it's worth. Welcome, and best of luck.

[robbspeed]

Welcome. What spark plugs did the dealership install, and what did you gap them to?

You're going to need Versatune if you wanna make more power with a cx7. You can live monitor a lot of different parameters and record datalogs which can help us figure out what's going on with your car. It will also allow you to read any trouble codes you might have in the future. Maybe get a compression tester while you're at it. Don't bring your vehicle to anymore dealerships or shops. Get it figured out with the help of msf.

Here's the link. Good luck.
https://www.versatuner.com/features/...cx-7-disi-gen1