[sleepyhead]

Around town with normal driving what should the a/f ratio be or at least a range. I believe 14.7 is good not under WOT. I'm a newb and I've been doing some reading so I am just trying to get a better understanding. I have the cobb ap stage 1 and under WOT its like 11.2 which i've read is good. Thanks

[520]

Your fine.

[wrxtasy]

the lower the number the more fuel will be added per unit of air

ex. 14.7 is perfect if memory recalls, but thats on a NA car. anyway 14.7 means 14.7 parts air to 1 part fuel. 10.2 would be 10.2 parts fuel to 1 part air, resulting in a more rich a/f ratio.

[sleepyhead]

When I get off the gas and just coast it goes up to 20 something, I assume thats normal.

[vovik05]

What are the danger zones under WOT?
When under WOT my AP shows it at 11.0 could it even read any lower? Seems it may be hitting some sort of lower limit maybe limit for the readout but in actuality it is lower still? Is that possible?

[RallySportDirect]

The AP is not accurate at giving the AF ratio. As the Stock O2 sensor is out of range lower then 12.5:1. As its only meant for emissions.

With that being said. Our car was at 11.5:1(wideband on dyno), with a AP OTS map, Invidia Catless DP, APS manifold, and Drop in filter.

[vovik05]

Interesting. So 11.5 is fine, correct? What would be a bad AFR reading? Or does it really depend on the tune?

[RallySportDirect]

11.5;1 is about as lean as you want to go for a turbo car. Unless you are running on race gas.
For safety, 11.0:1 is about where you want to be in a Force Induced car.

[STiProsDoc]

Originally Posted by RallySportDirect

11.5;1 is about as lean as you want to go for a turbo car. Unless you are running on race gas.
For safety, 11.0:1 is about where you want to be in a Force Induced car.

Don't you mean "as rich"? lower number indicates greater amount of fuel/less air (hence rich) and higher number means less fuel/more air hence lean

[flatthump]

Originally Posted by STiProsDoc

Don't you mean "as rich"? lower number indicates greater amount of fuel/less air (hence rich) and higher number means less fuel/more air hence lean

Air-fuel ratio - Wikipedia, the free encyclopedia

OP: The stock 02 sensor is a narrow band design. Like RSD said, it doesn't have the ability to accurately read AFR's. It's basically just a lean or rich switch.

[tshrey]

Originally Posted by STiProsDoc

Don't you mean "as rich"? lower number indicates greater amount of fuel/less air (hence rich) and higher number means less fuel/more air hence lean

No, he means lean. You don't want to go higher than/leaner than 11.5:1 AFR on WOT in a forced induction car (unless you have meth ).

Light throttle driving the ECU tries to keep you at stoichometric (14.7:1).

[importfanatic17]

Flat, it says this in that link...Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture...???

I think I am at like 12 or somewhere around there so I still have plenty of room to lean it out. <--See, I say it that way too but the link says the opposite.

[flatthump]

Originally Posted by importfanatic17

Flat, it says this in that link...Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture...???

I think I am at like 12 or somewhere around there so I still have plenty of room to lean it out. <--See, I say it that way too but the link says the opposite.

They just say that cause it's either richer or leaner than Stoich.

Car enthusiasts use the word to either say what direction they are tuning fuel in, or if they are running in either of the extremes.

I don't think you're running 12:1. I hope not....not on Cali 91.

[importfanatic17]

^^It is piss gas and I honestly just made that number up. I didn't even ask Ed what I was running b/c I trusted he would know what is best.

I'll find out what I'm running WOT and stop making up internet lies .

[jimmyz80]

Any readings you get from the onboard O2 sensor you might as well just pick random numbers. Take it to a dyno shop and put a wide-band O2 sensor in there. That's the only way to get a reading you can trust.