Air / Fuel ratio question
Thread Starter
Race Director
Joined: Nov 2000
Posts: 10,340
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From: Beverly Hills (Pine Ridge) Florida
Air / Fuel ratio question
Does anybody have a correlation of air fuel ratio to O2 sensor volts? I have a Diacom which reads the O2 volts, but need to know what those volts mean in the ratio of air / fuel (understand that the higher the voltage, the richer the mix, etc.).
The Diacom also reads out the Air/Fuel Command ratio, but I need to know how close the actual ratio is (especially when I adjust the fuel pressure, etc.
Thanks,
Plasticman
The Diacom also reads out the Air/Fuel Command ratio, but I need to know how close the actual ratio is (especially when I adjust the fuel pressure, etc.
Thanks,
Plasticman
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From: Hillsboro OR
Re: Air / Fuel ratio question (Plasticman)
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From: Former NCM Drag Racing coordinator, National director Corvette Challenge Spring Hill, Tennessee: Whiting, New Jersey
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Re: Air / Fuel ratio question (AquaMetallic94LT1)
:cool:, thanks :)
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Team Owner
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From: SE NY
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Re: Air / Fuel ratio question (Plasticman)
Be aware that in closed loop at part throttle the O2 sensor value will toggle between high and low (rich and lean).
In open loop at WOT my O2 sensor reads a steady 920mV or so on the AutoXray. Recent dyno pulls in 3rd gear at WOT with a wide range sensor showed 12.6-12.8 as the A/F, which is just about ideal. So for my setup I can now use the 920mV value as a good approximation for tuning when I increase air flow.
In open loop at WOT my O2 sensor reads a steady 920mV or so on the AutoXray. Recent dyno pulls in 3rd gear at WOT with a wide range sensor showed 12.6-12.8 as the A/F, which is just about ideal. So for my setup I can now use the 920mV value as a good approximation for tuning when I increase air flow.
Melting Slicks
Joined: May 1999
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From: Sarasota FL
Re: Air / Fuel ratio question (Plasticman)
Just make sure you realize the only thing a stock O2 sensor is good for is a rich lean switch. Varying temps, pressures, and age of the sensor could make 850mv mean 12:1 or 14:1. In other words, the mv readings given by the O2 are almost useless for determining AFR.
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Instructor
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Re: Air / Fuel ratio question (Aaron's 87)
Wow! Someone that agrees! My info says the ratio can vary up to a full number, i.e. 12:1 to 13:1,
so I'm being a bit more lenient than you, Aaron. But a full point variance is still too much to be
considered accurate or of any meaningful/useful info. On a forced induction application its suicide!
so I'm being a bit more lenient than you, Aaron. But a full point variance is still too much to be
considered accurate or of any meaningful/useful info. On a forced induction application its suicide!