Does E85 Flex Require a Dual Tune?

[Vanishing Point]

I have moved to Dallas about a year and a half ago and have had a hard time finding a decent builder/tuner. There are too many issues to mention, but one interesting question I figured was a quick answer for you guys. One shop said for E85 flex (run it on E85 usually and premium gasoline when E85 is not available), it requires 2 tunes, one for gas, one for E85. The next shop said no, just one tune on E85 and the car’s computer will figure it out for the gasoline adjustment. Keep in mind some other changes were occurring which would necessitate a full retuning so it wasn’t just the addition of E85 to consider. The first one (dual tune) seems to make the most sense, but they were shady as hell so it might have just been a way to double the tuning charges. So is it 1 or 2 tunes required? Thanks.

[ChibiBlackSheep]

I agree with the second shop. When you do a flex fuel tune, you are installing a sensor that monitors the % of ethanol in the gasoline, and then cross references against that table for timing.

I could see the first shop just making the high octane table the e85 table, and then the low octane table the premium table, which I don't believe is the correct way to do it.

[Vanishing Point]

Originally Posted by ChibiBlackSheep

I agree with the second shop. When you do a flex fuel tune, you are installing a sensor that monitors the % of ethanol in the gasoline, and then cross references against that table for timing.

I could see the first shop just making the high octane table the e85 table, and then the low octane table the premium table, which I don't believe is the correct way to do it.

I think I see what you are saying. My original thought was that once the sensor picks up the % of ethanol, it adjusts to the second tune to the degree the fuel % requires. If no second tune (gas) how would it know toward what tune to incrementally adjust to.

But if I’m picking up what you’re putting down, it (the car’s computer) knows how to adjust the tune because the change needed is not an unknown, it is calculable based on the known factors (like a universal octane table) that occur due to that change in fuel %, which would require the same adjustment to any starting tune for any vehicle. In other words, it’s not incrementally adjusting TO a second tune, it’s incrementally adjusting FROM the first (E85) tune by amounts of the universal table to which the car computer knows. If I understand that right, then that makes sense now too. Thank you.

Still would love to see that others agree or disagree.

[Clarkstar]

You need 2 tunes. One for gas, empty the tank and fill with e85. Retune...

Then the computer will adjust based on the alcohol content detected by the sensor.

[dreksnot]

The Camaros originally don't have the Flex Fuel sensor installed but the tune has empty tables (unpopulated) for flex fuel. Simple enough to install the sensor inline in the fuel system. Once installed correctly, a tuner can make adjustments in the tune (populate the appropriate tables in the tune) to account for ethanol in the fuel. Depending on how much E is in the fuel, the tune can add/subtract timing, thus taking advantage of ethanol characteristics (generally it can add up to 6-8* timing making more power). With non-forced induction applications, it really doesn't account for much power, maybe 10. But, with forced induction, it can really shine, providing 80-125 more HP.

If the tune was done correctly, you can put whatever in the tank. 0% to 85% E fueling (all 91/93 octane, all E85 or any mixture blend of it) and the computer will determine how to run with that. Two tunes ARE NOT REQUIRED (unless you do not install the sensor).

[Vanishing Point]

Originally Posted by Clarkstar

You need 2 tunes. One for gas, empty the tank and fill with e85. Retune...

Then the computer will adjust based on the alcohol content detected by the sensor.

My ignorance is a bit like being high. You can put together connections on anything and make it all seem feasible. So thank you for your word on this as well.

Seems I’m where I started, one says 1 tune, one says 2 tunes. Any more contributions? I figured this to be an easy one, I’d be annoying people with because it didn’t warrant a thread. Guess I may have been wrong on that.

I also figured that, while different theories may make sense, experience in the field would dictate a clear choice. I’m beginning to think that may not be the case either, and that you could do it with either 1 OR 2 tunes. Maybe 1 tune would get you by but not be as precise as 2 tunes. I don’t know. I’ll shut up and let you who know something speak.

[Vanishing Point]

Originally Posted by dreksnot

The Camaros originally don't have the Flex Fuel sensor installed but the tune has empty tables (unpopulated) for flex fuel. Simple enough to install the sensor inline in the fuel system. Once installed correctly, a tuner can make adjustments in the tune (populate the appropriate tables in the tune) to account for ethanol in the fuel. Depending on how much E is in the fuel, the tune can add/subtract timing, thus taking advantage of ethanol characteristics (generally it can add up to 6-8* timing making more power). With non-forced induction applications, it really doesn't account for much power, maybe 10. But, with forced induction, it can really shine, providing 80-125 more HP.

If the tune was done correctly, you can put whatever in the tank. 0% to 85% E fueling (all 91/93 octane, all E85 or any mixture blend of it) and the computer will determine how to run with that. Two tunes ARE NOT REQUIRED (unless you do not install the sensor).

It has the sensor. It has been added along with the new fuel system to tolerate the corrosiveness of E85. Thanks.

[Black_SS10]

If the car has never been tuned, it will most likely be tuned twice. One with 93 and another with E85. Once that is done the tuner does their magic. The sensor detects the % of alcohol, timing is added/removed based on that percentage and the octane tables. Also, make sure they don't tune e85 for only WOT.

[rgrmoreira13]

Originally Posted by Vanishing Point

I have moved to Dallas about a year and a half ago and have had a hard time finding a decent builder/tuner. There are too many issues to mention, but one interesting question I figured was a quick answer for you guys. One shop said for E85 flex (run it on E85 usually and premium gasoline when E85 is not available), it requires 2 tunes, one for gas, one for E85. The next shop said no, just one tune on E85 and the car’s computer will figure it out for the gasoline adjustment. Keep in mind some other changes were occurring which would necessitate a full retuning so it wasn’t just the addition of E85 to consider. The first one (dual tune) seems to make the most sense, but they were shady as hell so it might have just been a way to double the tuning charges. So is it 1 or 2 tunes required? Thanks.

Well no.
You will need to get the car tuned to receive E85. However your tuner will have the parameters to change the timing if your E85 content reaches a certain percentages. Because even if you run pure 93 it will still have some Ethanol in the gas and will have around 10% of E. so yea I would honestly go with your second tuner.

[Clarkstar]

Originally Posted by Vanishing Point

My ignorance is a bit like being high. You can put together connections on anything and make it all seem feasible. So thank you for your word on this as well.

Seems I’m where I started, one says 1 tune, one says 2 tunes. Any more contributions? I figured this to be an easy one, I’d be annoying people with because it didn’t warrant a thread. Guess I may have been wrong on that.

I also figured that, while different theories may make sense, experience in the field would dictate a clear choice. I’m beginning to think that may not be the case either, and that you could do it with either 1 OR 2 tunes. Maybe 1 tune would get you by but not be as precise as 2 tunes. I don’t know. I’ll shut up and let you who know something speak.

I recently converted to e85... maybe the confusion is that there aren't technically 2 separate tunes... but the car needs to be tuned twice.

You install the sensor, take your car to the tuner. They tune it on premium. They empty the tank and fill it with e85. Then they tune it on e85.... the computer will compensate for 0-85% alcohol content.

[dreksnot]

Originally Posted by Vanishing Point

It has the sensor. It has been added along with the new fuel system to tolerate the corrosiveness of E85. Thanks.

The Camaros could already handle the "corresiveness" of E85, no changes required; however, PTFE hoses prevent the "bleeding" of fuel smell from escaping. It's the old days of rubber, susceptible to E systems that need upgrading. Anyway, if you've upped the fuel system to handle the 30% more fuel volume requirement compared to pump gas, you're golden. That includes fuel pump, fuel injectors and that FF sensor.

[dreksnot]

Originally Posted by Clarkstar

I recently converted to e85... maybe the confusion is that there aren't technically 2 separate tunes... but the car needs to be tuned twice.

You install the sensor, take your car to the tuner. They tune it on premium. They empty the tank and fill it with e85. Then they tune it on e85.... the computer will compensate for 0-85% alcohol content.

[Vanishing Point]

Originally Posted by dreksnot

The Camaros could already handle the "corresiveness" of E85, no changes required; however, PTFE hoses prevent the "bleeding" of fuel smell from escaping. It's the old days of rubber, susceptible to E systems that need upgrading. Anyway, if you've upped the fuel system to handle the 30% more fuel volume requirement compared to pump gas, you're golden. That includes fuel pump, fuel injectors and that FF sensor.

Yep. All of that has been upgraded. She can chug it down like a frat boy does beer.

[Vanishing Point]

Originally Posted by dreksnot

@dreksnot: Just to make sure I understand what happened here. You earlier said, “Two tunes are NOT REQUIRED”.

Then you gave a thumbs up to Clarkstar when he said that they will have to tune it on gas, drain it and tune it again on E85.

That leaves me a little confused. So are you agreeing (implied by the thumbs up) that it will require 2 tunes? And are you agreeing with Clarkstar that the only confusion has been semantics? If what Clarkstar is saying is the agreed upon conclusion, then I would definitely say that’s 2 tunes and credible to charge for 2 tunes. If the only thing at debate is whether the second tune is stored in the car’s computer as a tune or as a table of settings, that’s kind of moot, and very misleading to say only 1 tune is required.

Is that the page that everyone else is on as well? That tuning it twice and draining it in between is the proper method (regardless of whether you call that 1 or 2 tunes)?