Had flexfuel engines not been somewhat mediocre, would ethanol be more widely accepted?

[redpoint5]

I'd be willing to test it if Oregon had anything higher than E10, but color me skeptical considering the loss in MPG on my Subaru when we went from E0 to E10.

[roosterk0031]

I've only filled with E30 from a blender pump a few times. The 2010 cobalt was fed E30 for most of 2 years because my daughter had a blender handy and was cheaper.

http://www.speedperf6rmanc3.com/cont...evel_Study.pdf

This study did a better job of documenting FE. While the other one explains why.

[gone-ot]

The vast difference in stoichiometric A/F ratios between straight ethanol (9.001:1) and gasoline (14.7:1) quantifies its huge loss in MPG numbers; of course, its octane is much higher.

[redpoint5]

So running E30 in a non-flex fuel vehicle would tend to create a lean burn considering Ethanol wants a lower AFR than gasoline, yet the ECU will target a gasoline AFR?

[gone-ot]

...yes, but SOME Flex-Fuel vehicles actually 'test' the fuel for % of ethanol, so automatically compensate.

[roosterk0031]

ECU targets stoich. O2 sensor is just watching for no excess O2 and will adjust Long term fuel trim as required.

Since it takes less air for complete combustion the car thinks it's injection to much fuel per the volume of air. So the LTFT goes positive relative to what it would be for E0-10 for the amount of air the MAF is seeing. Somewhere around +25 it will throw a Lean code P0171, even though it probably isn't.

FFV cars can have an advantage because the can learn or use a sensor to detect the E content and change timing and other tables to optimize it. Tuners who have looked at some of GM's FFV tables don't think they tried very hard to get the most out of the fuel at least in 8+ year old ones.

The impala doesn't have a sensor, after a refueling event to goes through a learn procedure to figure out the E content, your supposed to drive a certain time or distance after refueling or it might not work.

My XFE had an intermittent failure of a fuel injector recently, since at times it wasn't injecting any thing. O2 sensor saw free O2, cranked up the LTFT to 28, STFT to 32 giving me a P0171 and flooded the other 3 cylinders causing a misfire. Took a few weeks to figure out, started with O2 sensor ($35), plugs and coils $125, finally injectors for $113. Not bad for just hitting 250,000 last week.

[redpoint5]

My Acura has a MAP sensor. Is one inherently better/worse than the other?

If I understand correctly, the ECU doesn't know what the AFR actually is, it just knows how much O2 is going unburned, and adjusts fuel to target stoich, so it doesn't really care if it's ethanol or gasoline.

I've never seen my car go more than 40 degrees advance, so I'm not sure if there is any benefit by going more advanced than that, or of the car is even capable to do it. Of course, the car could tolerate more advanced timing under load with higher octane, but I'm not sure that's much of a benefit considering most of the time is spent cruising, not accelerating.

All that said, Nothing over E10 is readily available in Oregon. I just found a pump with E0 premium (92 PON), but it's $1.20 more expensive than regular 87. I might try blending with regular (E10) to see how it affects MPG.

[roosterk0031]

I imagine MAP or MAF measure air flow good enough. The cobalts have both I don't know if the MAP works as a back up? They don't have to be precise, just consistent, the LTFT will adjust.

Yep, car doesn't care what the fuel is until it exceeds the fuel trim limits.

Wife filled the 15 Rogue with E85 shortly after getting it out of habit with the Impala. Next day I noticed it didn't start as instantly as normal, after a few mile the light came on and figured out what she did. Ran fine the whole time.

The link in #9 shows how much timing is retarded with E0 vs E30. I can't tell with the SG2 if my timing changes any with blends. If I gained the same 4 hp as the Malibu with almost the same engine as the cobalts I don't think I could feel it.

[redpoint5]

I'm curious how much extra it actually costs refiners to produce 87 vs 92 octane fuel? They reduce the octane of the gasoline they blend with E10 so that they aren't giving away octane for free.

Starting to come around on the ethanol subject since there is plenty of evidence that an engine built for high levels can be very powerful and efficient. I stick to my assertion that the market would have built this already if power was improved and cost of fuel per mile were cheaper. More power for cheaper; that checks everyone's boxes.

[roosterk0031]

A few years ago here E10 was 89 octane, E0 was 87 that was the base blend. The refiners switched the base fuel to 85 octane, E10 now is 87, E15 is 88. To get E0 - 87 they have to blend premium with the 85 making the price way higher than E10. Like you said they were giving away octane.

I've read articles on raising the minimum octane in the US to make it easier for car manufactures to meet future FE goals.