'03 Cobra motor AF Ratio question...

[1991notchbackLX]

Hey guys, I just installed my AEM UEGO wideband O2 sensor yesterday on the A pillar of my 99 GT. The car has an '03 cobra motor in it with a 3" pulley and a supposedly "safe" 93 octane tune. The car made 455/457 on the dyno at 12.5 pounds of boost. The wideband is reading between 14.7 and 15.4 for my AFR while idling and during cruising around at lower RPMs. I went WOT and it flashed to mid 12s. I would like some help as to what it should be for safety. I'm hoping it's tuned a bit rich to be more forgiving. I don't have much experience with supercharged cars, so I'm not sure what I should be looking for. Any help would be greatly appreciated. Thanks so much!

Chris



Cliff's notes: what should safe AFRs be at cruising and WOT for an '03 cobra motor with a 3" pulley and tune making 455/457 @ 12.5 lbs boost

 

[BurningRubber]

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).

 

[srtthis]

11.5-11.8 if you need a new tune lemme know my tuner is VERY good with the 03s!
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[1991notchbackLX]

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

 

[LaserSVT]

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.

 

[srtthis]

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

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