Adjusting Stoich 14.3 - Effects on O2?

[Schmieder]

So I am setting stoich to 14.3 for reasons of 10% ethanol and boost.

Though, I read the O2 sensor has a very narrow area of accuracy at 14.7

So, will I have issues if the PCM is aiming for 14.3 but the O2 sensor losses its accuracy at that range? Cause it seems the PCM will command 14.3 and when it gets there, the O2 sensor will say, "Hey, I'm rich but I don't know how rich."

Or is 14.3 in the boundries of a NBO2's accuracy range?

I know people are doing the stoich tune to 14.3 with great success. Are they doing so with WB's?

Thanks guys

[robertisaar]

don't believe everything you read on the internet...

NB02s are most accurate near stoich ratios, which is different depending on each fuel. so if your fuel burns at a stoich ratio of 5:1, then you NEED to set the target AFR to 5:1, or else the PCM will continually try to adjust to an AFR that doesn't sit well with the O2.

more or less, you're reading too much into it.

if the fuel you choose to run burns at a stoich ratio of 20:1 or at 5:1, the O2 will read the oxygen content in the exhaust. if there is excessive amounts of O2, it will attempt to richen the mixture, regardless of what you tell it the AFR is. the PCM will eventually land on a spot that it will like, but it takes FAR too long to just leave it.

think of it this way: 1 O2 can be used for diesel, gasoline and E85. no changes are made to it at all(and for sake of simplicity, lt's say this one engine runs all three). and let's temporarily call MAFs perfect. if the PCM is told which fuel is running at any time(whether through user interaction or some type of fuel sensor), it SHOULD adjust target AFR to match the fuel and the O2 will not need to correct at all due to the ECM knowing exactly how much air is entering the engine and what AFR to run at?

make sense?

[Schmieder]

don't believe everything you read on the internet...

NB02s are most accurate near stoich ratios, which is different depending on each fuel. so if your fuel burns at a stoich ratio of 5:1, then you NEED to set the target AFR to 5:1, or else the PCM will continually try to adjust to an AFR that doesn't sit well with the O2.

more or less, you're reading too much into it.

if the fuel you choose to run burns at a stoich ratio of 20:1 or at 5:1, the O2 will read the oxygen content in the exhaust. if there is excessive amounts of O2, it will attempt to richen the mixture, regardless of what you tell it the AFR is. the PCM will eventually land on a spot that it will like, but it takes FAR too long to just leave it.

think of it this way: 1 O2 can be used for diesel, gasoline and E85. no changes are made to it at all(and for sake of simplicity, lt's say this one engine runs all three). and let's temporarily call MAFs perfect. if the PCM is told which fuel is running at any time(whether through user interaction or some type of fuel sensor), it SHOULD adjust target AFR to match the fuel and the O2 will not need to correct at all due to the ECM knowing exactly how much air is entering the engine and what AFR to run at?

make sense?

AAaaaahhh, I get it. Stoich is a perfect condition and the NBO2 is best at detecting this condition.

In reality, setting stoich to 14.7 when burning gas w/ 10% ethanol is the issue. Cause stoich is 14.1'ish w/ 10% ethanol.

After reading the first few lines of your reply, it all hit me.

Thanks

[robertisaar]

AAaaaahhh, I get it. Stoich is a perfect condition and the NBO2 is best at detecting this condition.

In reality, setting stoich to 14.7 when burning gas w/ 10% ethanol is the issue. Cause stoich is 14.1'ish w/ 10% ethanol.

After reading the first few lines of your reply, it all hit me.

Thanks

exactly. the O2 doesn't care what fuel is being run, just that there is a perfectly stoich ratio.