'03 Cobra motor AF Ratio question...

I'm not a tuning genius by any means, you NEED to be richer than mid 12's under WOT. That is getting lean for a forced induction car.

With the amount of boost you are making, 11.8-12.0 is the max I would personally want my car at, and preferably at 11.8.

As far as cruising A/F ratio, you are probably fine where you are at as long as it richens up under boost. Under normal conditions, you are making no, to very little boost and aren't spinning the motor very hard.

Is your wideband using 1, or 2 sensors? If it's 1, switch to the other bank and see what it's reading under the same conditions. Sometimes things can get screwy and one bank of cylinders will be leaner/richer than the other.


Generally, you are looking for 11.6-12.2 forced induction or nitrous (this number depends on your setup, some may even want to be richer), and 12.8-13.4 all motor (again, this depends on the setup).

11.5-11.8 if you need a new tune lemme know my tuner is VERY good with the 03s!
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11.5 would be optimal under WOT. Where is the wideband O2 mounted? If its in the second OEM O2 loation then it will read .2-.4 leaner then it actually is. If its at the collector then it will give a more accurate reading. 12 is running a bit lean but at 455 you are not dangerous running at 12.0 AF. Does it have the stock MAF? Cause at 425-440 rwhp it is pegged and will cause lean/rich issues.

1991notchbackLX said:

Thanks for the help guys. SRT, I live in NY. Where is your tuner located?

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hes in south carolina but he does remote tuning stuff just gotta set up something with him...