My corn vs corn free gas comparison test

[Broncojohnny]

Any guesses on why?
Is a '98 smart enough to tune on the fly? I thought those years didn't have knock sensors (only the DOHC Cobra stuff did) so there wouldn't be timing adjustments or anything else going on.

Don’t think there is a knock sensor. My thought is that if one cylinder knocks 1% of the time it can make a difference. Tolerance stacking again. Also not sure about newer computers but the old EEC IV’s could adjust fuel +\- 20% which is enough to change results too. The O2s are sensing oxygen and the computer is seeking AFRs that are for gasoline.

One other thing to consider in any of these tests and it is overlooked very often, is windage. Run any of these tests with the engine full of oil. Then drain a quart and run them again. It can be a huge difference.

[johnboy]

Ok, I've been looking for the papers I had all this on but can't find the one where I noted miles between tanks. I moved out here sept 2015 and did the test around oct and nov. I would leave at 5:30 a.m. and leave work at 3:30. Definitely more traffic going home. I would gas up Fri on the way home and refill on Wed. I sold it back to the original owner early 2016 and bought a accord from a coworker for better mileage and drove that until it had a rod knock. I bought the stang back last year for cheap, but it was parked until I had neck surgery and could turn my head again. I've been driving it to richardson 3 times a week for therapy and it averages around 24, but that's more city and traffic driving from getting there at noon and leaving at 1:30. I usually fill it up at around a quarter tank so that might factor in also.

I only use the non-ethanol in mower now, but might try this again. I'm going to check the price when I fill my gas can and I'm going to ask who they buy it from.

[Strychnine]

Also not sure about newer computers but the old EEC IV’s could adjust fuel +\- 20% which is enough to change results too. The O2s are sensing oxygen and the computer is seeking AFRs that are for gasoline.

Stoich for E10 is lower (14.1) so with a carb it would lean out, but an EFI shouldn't shouldn't be seeking 14.7 AFR anyway. I thought pretty much every OEM EFI out there runs narrow band O2, detects excess O2 (Lambda), and adjusts based on the "1.0 Lambda = stoich scale."


(Modern gas EFI starts to pull me outside of my comfort zone)

[Broncojohnny]

It will seek the same amount of oxygen. Saying AFRs was not really accurate, what you say is correct. If it needs to add or subtract more than the 20% then it stops at the top or bottom of the 20% range. That is why if you fill one up with E85, it will run like crap, it can't add enough fuel to get to the value it is seeking. However, if you fill the tank with half E10 and half E85 the EEC IV mustangs seem to be able to compensate. My old 95 GT would do this. Only on really cold mornings did it ever even hiccup once.

For my junkyard wars 89 T bird SC we did the "tuning" in true junkyard fashion. The car came with 36 lb injectors from the factory. We just plugged in 52 lbers and did nothing else. The idea being they are a little over 30% bigger and E85 requires about 30% more fuel. Car runs great and has no idea it is running on E85, the extra injector size gives it the ability to adjust and find the point it is looking for inside that +/- 20% range. The latent heat of vaporization effect makes it sing with the M90 Eaton though, it is a night and day difference because those blowers heat the air like no other and the E85 takes that heat out of the air.

[Strychnine]

This...

If it needs to add or subtract more than the 20% then it stops at the top or bottom of the 20% range. That is why if you fill one up with E85, it will run like crap, it can't add enough fuel to get to the value it is seeking. However, if you fill the tank with half E10 and half E85 the EEC IV mustangs seem to be able to compensate.

Combined with this

We just plugged in 52 lbers and did nothing else. The idea being they are a little over 30% bigger and E85 requires about 30% more fuel. Car runs great and has no idea it is running on E85, the extra injector size gives it the ability to adjust and find the point it is looking for inside that +/- 20% range.

definitely makes sense and gives some context.

Doesn't explain OP's situation, but it helped me.

[4king]

I remember the switch to e10, my 6 speed LS1 formula went from getting 18-19 mpg city to 16mpg.

I still regularly run non ethanol. The most consistent results were in my 96 Civic hx which had modern 5wire wide band oxygen sensor and an ECU that actively calibrated timing and fuel trims to maximize gas mileage

I went to Lubbock several times and average on e10 was 51 mpg, average on non ethanol was 56mpg.


The biggest variable is the shit co-op places that sell non ethanol gas. In Lubbock it's a major gas chain, other places it unbranded and probably contaminated tanks and Lord knows how old it is

[cool cat]

I went to Lubbock several times and average on e10 was 51 mpg, average on e10 was 56mpg.

What was the mileage on e10, 51 or 56?

[4king]

What was the mileage on e10, 51 or 56?

I had to re edit that

Non ethanol was 56

Lemme see if I can find my gas logs on ecomodder

[Grimpala]

Where in DFW can you buy non ethanol gas? I'm getting tired(so is my wallet) of running AV gas in the boat.

[garycrist]

Exxon Sherman @ SW corner of 82 and 75..

GL

[Grimpala]

Exxon Sherman @ SW corner of 82 and 75..

GL

I'll pay ~$4 a gallon for Avgas before driving to Sherman.