Originally Posted by gamefreakgc

I think for more modern vehicles that can run on E85 or traditional gasoline, they make the same miles per gallon? Something about able to advance timing to take advantage of the high octane fuel making more power per stroke and increase MPG's. Obviously our antiquating 4Runners don't have anything like that.

I have heard of complete E85 swaps like someone else is doing that did not replace the fuel pump and the fuel lines. There's very few rubber parts along that path so it wouldn't be terribly hard to convert them either to stainless steel or some other flexible line. Those would be the only two components that would not be able to handle the increased fuel needs of having to compensate for E15.

The ECU will read it like this: because E15 has less energy density it'll start to run a little lean. The oxygen sensor (or 2001 later vehicles, Air Fuel Ratio sensor) will immediately increase fuel trims to compensate. I don't see a scenario where it would ever increase the long term fuel trims over 30% and trip a code, I don't think even E85 would do that. Over time, the ethanol could start to cause the rubber to deteriorate to the point of causing fuel delivery options. The pump should continue to operate as it's always on at the same rate, it doesn't scale with throttle. I do not think that fuel pressure will drop as the 4Runner doesn't max out the pump if naturally aspirated.

Overall, I believe based on my work on the 5VZ platform we should be fine other than the obvious MPG drop as it's less energy dense fuel. California has been E10 only for about 5-6 years now and I have not had any problems except for watching my MPG drop. Below is a chart of the drop, you can see the baseline go down in 2017. It'll be less severe with a 5% add instead of 10% add but you get the idea.

Originally Posted by phattyduck

You have the "slower burn" portion correct - but you have to ignite the fuel EARLIER (advance the timing) to get max torque from higher octane/ethanol content.

Of course, E15 fuel with the same octane rating as E15 fuel would likely burn at the same rate. The rest of the fuel could be lower octane to make up for the extra ethanol content.

-Charlie

Originally Posted by JBurt

Well I've been running E15 since I have no alternatives, and I assume many people are in the same boat. The rig hasn't exploded yet.

Originally Posted by JoeT4R

Have you been consistently running it for a while? How's your mileage? And all other factors associated with it like tire size/type, lift/stock suspension, daily driving conditions etc.

So far I'm not noticing a huge decrease in performance, and it could totally be placebo, but I feel like my rig is a bit less responsive than usual.

Originally Posted by Zhehan

This is good information. I never thought about it like this before.

I have a piggyback tuner, the Perfect Power SMT-5, that I can use to advance the ignition timing, alter the fuel maps, etc. I will do some testing this month with it to see how much more timing advance I can get away with running E10 fuel. These engines are tuned pretty good from the factory regarding the timing maps with regular 87 Gasoline. The Fuel Maps are also pretty good in Closed Loop mode with the ST and LT functions dealing with live conditions. But, you can tweak the maps a bit here and there depending on said conditions.

I will also take a look at Fuel Trims with my Scan Tool. I'll report back to this thread after I have gathered some data. I'll probably take a few weeks of logging fuel economy and timing advance adjustments.

Originally Posted by gamefreakgc

Be very careful with timing advance. I at one point had thought about getting a piggyback that could retard and advance timing but then I decided against it. Too many times I've had to fill up with less than 91 octane due to the pump being empty, or my wife forgetting what kind to put in and puts in 87. If I were to have timing advanced on top of that it could get really bad really fast. In order to gain MPG's from running timing advance, it would have to be in cruising RPM's from 1500 to 2500 RPM. That's our engine achilles' heel when it comes to pinging, my worst ping sets in around 2200 RPM. I didn't see anything about your engine being supercharged so that'll give you a little bit of wiggle room but you might encounter it. Please do so in no more than 2 degree increments - that's the general rule for timing. Up it by 2, test, if works ok try 2 more. Also be aware that ambient temperature plays a huge role and if you tune it in a cold day in the 60's and then drive it on a hot day in the 90's the result will be much different.

Originally Posted by phattyduck

The 5VZ ECU ignores the knock sensor below 3k RPM, so it will always use the 'default' timing in that area of operation. Since it is tuned for 87 octane, any 'extra' octane will decrease instead of increase performance. 91/93 is needed for the supercharged guys for this exact reason (can't pull timing with knock below 3k rpm - extra cylinder pressure = ping in those situations).



If you still get sufficient performance with E15 and fuel trims are still reasonably good, it might be better for the pocketbook, if not for performance.



-Charlie

Originally Posted by Zhehan

Thanks. I appreciate the concern but I've had this tuner for decades at this point. I never aggressively tune. I have several setups saved for different scenarios. Around town driving you can be a little more aggressive with your tuning vs on the trail for instance.

Also since I have a manual transmission I can pretty much being whatever RPM range I want by simply shifting. 😜

At any rate, thanks again and I'll post some thoughts when I get around to playing with this some more this week.

Cheers.

Originally Posted by gamefreakgc

Yes I'd love to hear how it works out. It's a real shame our 4Runners cannot benefit from the ethanol that's becoming standard for fuel and this might be a way to do so. Really interested to see if you can boost up the MPG's.

Originally Posted by brillo_76

Hmm. Maybe a missed something in this thread. If so, I apologize. How is decreasing the fuels efficiency a good thing?

I mean if you are loosing efficiency at 10% of ethonal added into the fuel. How is loosing more efficiency a good thing?

If you have to buy more fuel, you are not only not going as far on a gallon. You are paying more in taxes on said fuel to go the same distance. :/

Originally Posted by phattyduck

You will always lose MPGs with ethanol compared to 'normal' gasoline, though not necessarily power (if you can tune for it). That part we are all on the same page with.

The question comes if the cost of higher ethanol gas is low enough to make up for the lower fuel economy.

Theoretical example:
E0 = 20mpg and $4.50/gallon ($0.225 / mile)
E10 = 19mpg and $4.00/gallon ($0.211 / mile)
E15 = 18mpg and $3.50/gallon ($0.194 / mile)

Clearly, even with the the lower MPG, total cost per mile can be better. This is why E85 (sometimes) makes sense for the end user. That, and it makes great race fuel for cheap!

-Charlie

PS. I am purposefully ignoring any discussions of whether or not ethanol actually should be in fuel from an environmental perspective...