Poor fuel mileage

[Malachias]

Bonnie 92 SSEi (Supercharged).
My since brand new with 58500 miles on it.
New wires and new plugs (OEM parts)
In a city drive, with A/C on full time (cool air) I´m getting only a 8.84ml/gal.
It´s a very bad gaz mileage...
Any tips or advice will be welcome.
Malachias (Brazil)

[GTP Dad]

Try replacing the O2 sensor if you have one this usually causes fuel mileage issues on cars in the US.

[HotZ28]

Any CEL's, if so what are they? Do you have access to a live data scanner, if so, can you check STFT & LTFT? Are you sure the ECM is not keeping the engine in open-loop. I have never heard of one get that bad of mileage while in closed loop!

[Malachias]

Originally Posted by HotZ28

Any CEL's, if so what are they? Do you have access to a live data scanner, if so, can you check STFT & LTFT? Are you sure the ECM is not keeping the engine in open-loop. I have never heard of one get that bad of mileage while in closed loop!

Thanks a lot GTP Dad for your advice. I´m going to check my O2 sensor.

Dear Hot Z28: Sorry about my illiteracy with the American abreviations:
What means CEL / STFT&LTFT ?
ECM means Engine Control Module? What is engine in a open loop ?
I know this is a stupid ask for you, but will be helpfull the answer in order to explain my mechanic your advice.
I have acess here at Brazil to OBD1 and 2 scanner. Is it good for the Bonnie?
If yes, what I need look for?
My best regards.
Malachias