Air Fuel Ratio Questions
10-20-2011, 10:15 AM
#1
Air Fuel Ratio Questions I'm sure this has been asked a million times just was curious. I dynoed my car this past weekend and checked out my afr's and at min was at 12.8 Max 13.6 and avg of 13.0 I have no clue how to tune just was wondering if these were good numbers on the loaded Mustang Dyno. Its basically a cam only car and put down 387rwhp with 410's I also added like 4 gallons of 100 in it mixed with some 93 before i got to the dyno i know it doesnt help at all but my car runs better with it for some reason. ever since i put the 100 sunoco in it its running like **** with 93 so i just mix some 100 in and it runs much better. But anyways just wondering about my afr's thanks.
10-20-2011, 05:55 PM
#2
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To me 13.6 is a tad lean,but depends on what o2 they were using. If it was a tailpipe sniffed it could be showing leaner than further upstream especially with cats.
10-20-2011, 08:11 PM
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Running increased octane is going to cause problems in the future. I suggest solving the problem, not using other fuels as a bandage.
Depends on the method of sampling. Did they use a wide-band O2 (preferred!) or a tail pipe sniffer? I bet it's the latter. Regardless, I agree that 13.6 is pretty lean. Ideally, I'd want it closer to 12.8-12.9, 13.2 at the highest. You're hiding some power in your fuel tune.
Do you have the stock MAF housing installed?
Depends on the method of sampling. Did they use a wide-band O2 (preferred!) or a tail pipe sniffer? I bet it's the latter. Regardless, I agree that 13.6 is pretty lean. Ideally, I'd want it closer to 12.8-12.9, 13.2 at the highest. You're hiding some power in your fuel tune.
Do you have the stock MAF housing installed?
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10-21-2011, 11:36 AM
#14
I also added like 4 gallons of 100 in it mixed with some 93 before i got to the dyno i know it doesnt help at all but my car runs better with it for some reason. ever since i put the 100 sunoco in it its running like **** with 93 so i just mix some 100 in and it runs much better.
10-21-2011, 01:54 PM
#15
If it's running that lean with a 100 mixture, you are likely experiencing detonation on straight 93. I shoot for mid 12's on the dyno in the tail pipe and low 12's with a WBO2 up front because they always run leaner on the street, no matter how perfect it's loaded in my personal experience. You also want to drop timing a little below peak power for the same reason.
10-21-2011, 02:26 PM
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I think that timing should be know for saying a re-tune is required. I think that if it has 28 degrees of timing running 100 will not do anything. It might be a bad plug or wire. There should be fuel added. Cobra killer is right on.
