here part 2

What does this all mean?

What we need to ask ourselves is what happen when you find a bad gas station which add water or the E85 has more contamination that what the engine/tune can tolerate.

Maybe David could advice what needs to be consider in the tune or other readings from the engine. Base on those metrics, implement maybe a safe-fail mechanism to avoid catastrophic failure in the engine....

If I have a track day, I'll buy E85 directly from a race fuel vendor. this case is when you know that the engine will be put into the test.

Water in e85 is bad for the motor (formic acid production goes up during combustion and gasoline/ethanol separation occurs in the fuel tank in extreme contamination cases), and for those reasons, water content in e85 is more tightly controlled than in pump gas. The station storage tanks even have to be different to control water uptake. Check out the 2009 govt report on E85 sampling. Out of 150 samples taken across the country, the average water content was only ~0.6%, and only two had more than more than 1% water (1.3, 1.4%).

As you suggest, it would have to be deliberate contamination for water content to be in excess of 2%. This would never happen during manufacturing, only at an unscrupulous gas station. While an ethanol content sensor may not pickup a change from 0.5% to 10% water, your engine would tell you. Fuel trims would definitely drift lean, and my guess is that the motor wouldn't run as smoothly, probably have crappy idle.

The real concern should be getting a tank of E85 with lower than usual ethanol content, and as far as I'm concerned, a flex fuel sensor is great for monitoring this because the chance of having water-contaminated E85 is very very low.

My only gripe with the flex fuel sensor is that your getting the reading after the fuel has been pumped into your car. Don't get me wrong it's better than nothing however what do you do when you fill your tank and then it reads e70? I have no interest in putting the car around for 200 miles due to a bad tank of gas. Or even worse what happens if it comes out to something like 50%?

I prefer to spend the 2 minutes it takes to test it with my little test tube thingy and confirm that its the % im looking for before I fill her up.

But then what happens if for example you're tuned on E85 and you come up to a gas station and it turns out to be E70 and you confirm it with your test tube... Then you go to another gas station and it turns out to be E75 for example... And the next one and the next one... Then you run out of gas and wished you had put in some E70 in the first place...

Anyway you shouldn't have any issues during cruising if it's E85 or E70 yes? Your only concern would be boosted runs or WOT?

^Haha well that is the issue. Can't say I've never been in that situation before...I'm not sure how to calculate what affect running e70 would have on your AFR's relative to if it were e85 but I'd guess it could richen things up maybe 1/2 a point?

Realistically the car would probably drive fine on e70 but yes, I would certainly not get on it knowing its not the same ethanol content my car is tuned for.

Its unlikely anyone will be running real E100 or E0 so the good thing is if your sensor is reading either it would be safe to assume you have a problem.

Well said!

Great follow up video and good closure.

And to the ones that have a wideband and daily their vehicles, one can easily tell the difference from the fuel they got tuned with and another fuel in which your AFR values will either be a good half-point to point off based on whether the E85 content is high or low during a part throttle boost pull of about 15PSI+- or so. I always look when I fill up, so make sure you do that too along with using all the whiz-bang hardware we have today. If it's breaking up at that point, yes Virginia, we have a problem.

This thread had reminded me how important it is to test the e85 before pumping in. I just ordered, from Buschur, earlier today a e85 tester. $15, a lot cheaper than the zeitronix and I will know what it is BEFORE it gets pumped in. If it tests bad I don't need to pump it in, Im running a dual map tune.

I once was not paying attention and filled up with e70, i got tuned on e85, care ran like **** and under boost broke up a lot. Huge noticeable difference.

If you were tuned for 11.5 AFR on E85 and filled with E70 your AFR would decrease but should still run OK, assuming moderate boost and timing advance. If you are tuned "on the edge" it may be different.

Once you are over 50% ethanol/50% gas you get 90% of the benefits of adding ethanol to gas.

Every car that's running tuned should have an AFR gauge and the owner should be educated.

I've been running Eflex in Australia now for over 4 years continuously. It varies from E70 to E85, depending on time of year, and I've never had any problems.

yeah i was running 30psi, e85 was my aggressive map

It's the other way around. If you were at 11.5 on good known E85, a good known E70 fill-up would make your car run pig rich.

:) too much ethanol on board when I added that post. Yes, AFR's would be lower with E70. Tuning AFR's in the mid to high 11's should provide room either way for some variation in E content.