MicroSquirt.com read only forum (Jan.15,2018)

I have a couple of questions about mixture and O2 sensors. I'm running a wide-band LC-1 sensor.

Can you actually get a lean signal if you run way, way to rich? IE: if you dump so much fuel into the cylinder that combustion doesn't happen, will you still get a rich signal. I would think there would be even more oxygen than if you were running the right mixture since it's just passing straight through the cylinder w/o burning.

Also, how does an O2 sensor actually read O2? Is it just a percentage of oxygen contained in the "gas packet" that flows over the sensor? So if you're burning gasoline and you're running 14.7 a/f ratio, is there a drastically different amount of oxygen in that "gas packet" than if you were burning say, ethanol, at 14.7 a/f ratio?
Ethanol has a stoich a/f ratio of ~9. So if you ran gasoline at 14.7:1, and ethanol at 9:1, which "gas packet" that the O2 sensor reads would have more oxygen?

Maybe it's more accurate to talk about lambda instead of a/f ratio?

re the first part of your post.

if you are too rich you will get too rich misfires. misfier=no combustion= lots of oxygen in the exhaust pipe = lean reading.

i'm not sure about the second part of your question...
yes o2 sensor basically tells how much oxygen (in %) is in the environment (normally exhaust pipe). This $ of oxygen value is represented as a/f ratio i believe. 14.7 doesnt really mean anything, it's just a number. it's a stoich value (complete burn, i.e. all air is burned with fuel) for gasoline. lambda is basically a/f ratio represented in terms that do not depend on type of fuel used (different types have different stoich values).

What happened to this post? Why did it get duplicated so many times?

Wayne,

This happened because of an interesting hacker attack. Unlike previous attacks, which exploited security vulnerabilities in the forum software, this one used an invalid email address that caused the SQL queries to the database to fail, and created all sorts of problems (like the duplicate posts).

I *think* we have this sorted now. We'll keep an eye on it for the next few days...

Lance.