How does OAR work on e30?

[Stkid93]

Does OAR effectively work as an ethanol sensor? For example if you have a tune for e30 and you only have e20 in the tank. Will the OAR fall below -1? Letting you know that the ethanol content is too low?

from what I understand when using pump gas the oar reads the quality of the gas. And if you use 91 octane on a 93 octane tune. The oar should go down. So I’m wondering if it works the same with ethanol content.

 

[Intuit]

Doesn't directly check/test/analyze the fuel at all. ECU takes a "trial and error" approach, adjusting engine operating parameters based upon the presence of knock.

 

[gtx3076]

Does OAR effectively work as an ethanol sensor? For example if you have a tune for e30 and you only have e20 in the tank. Will the OAR fall below -1? Letting you know that the ethanol content is too low?

from what I understand when using pump gas the oar reads the quality of the gas. And if you use 91 octane on a 93 octane tune. The oar should go down. So I’m wondering if it works the same with ethanol content.

Yes, it will drop if your mix/tune are mismatched. I know because I tried the 87+E85 mix because some guys claimed there was enough additional octane in E85 that filling with 93 wasn't necessary. On full stock hardware, including plugs, I tried 87 and E85 and after a single log for E30 I saw my OAR's drop to -0.99 or something. I went back to the gas station and topped off with a little more E85 and it didn't drop again.

I decided it wasn't worth messing around with a different ratio mix so I still fill up with 93 for my mix.

 

[Stkid93]

Yea I don’t Mess around with 87. The problem with that is most people will tell you to do 3 gallons of e85 to make e30. And I think a good amount of people don’t test their ethanol. My station tests between 68-75. So if I were to do 3 gallons. My mixture would be more like e23-25 and that’s assuming the pump gas had the maximum 10% Ethanol. (Iusually end up having to do about 4.5-5 gallons instead of 3)

And if e23 was mixed with 87 octane. That’s even worse. So you are 7% under on ethanol content. And you lose 6 points on octane. Doing some very basic math I estimate that e23 with e87 octane comes out to 89.75 octane. Even if it was a proper e30 mix with 87 octane you are still only looking at 90 octane.

Now doing the same math with 93 octane instead of 87. You are looking at closer to 96 octane.

In any case it’s super interesting that your oar reacted like that even when mixing in ethanol. It has to be pretty darn sensitive in order to do that.

 

[gtx3076]

I don’t test ethanol. I just monitor my OARs a few times each season (summer gas/winter gas). My OARs have dropped below -1.00 so few times I can’t count more than the one I told you about.

 

[slopoke]

I would assume that it would work, as long as you have the hardware that will measure real time ethanol content and a tune that will adjust in real time as well. I guess it would be a modified "Flex Fuel" setup. I don't know if the stock ECU can incorporate a flex fuel tune.

 

[Jason@dizzytuning]

You would start a lot less new threads, if you read my tech articles on my website.

 

[Stkid93]

I’m sorry guys I know i start a lot of threads and it’s probably annoying. I’m just trying to learn and I ask a lot of questions when I try to learn stuff.