e85 w/o flex fuel kit?

[zkahle]

Also mine would probably be a tad quieter than urs since you have the single exit, while mine is the dual 4" exit.

[zkahle]

Originally Posted by phrosty

The main benefit of a proper flex kit is not having to wait for fuel trims to learn your E%. With a tune, transitioning from E85 to 93 is a bit interesting.

How so??

[kchar]

The flex-fuel kit allows the car to automatically/dynamically apply different fueling based on the percentage of ethanol through tables stored in the tune. Let's say you have e85 in your car and the ecu has adjusted and then you fill up with e60 some time later. The car will need to lower the amount of fuel being given because the lower e-content. This is done, basically, by looking at the amount of fuel currently being used and the resulting afr and then adjusting it to hit the correct target afrs.

Originally Posted by zkahle

How so??

[zkahle]

Originally Posted by kchar

The flex-fuel kit allows the car to automatically/dynamically apply different fueling based on the percentage of ethanol through tables stored in the tune. Let's say you have e85 in your car and the ecu has adjusted and then you fill up with e60 some time later. The car will need to lower the amount of fuel being given because the lower e-content. This is done, basically, by looking at the amount of fuel currently being used and the resulting afr and then adjusting it to hit the correct target afrs.

Oh kchar there is nothing I can't post that you won't see on this forum lol.

[kch]

Originally Posted by zkahle

Oh kchar there is nothing I can't post that you won't see on this forum lol.

To expand on what kchar said, it's a pain in the ass to switch back and forth without a flexfuel kit. You basically have to run the tank until empty before you can switch fuels, and that's not always convenient.

[jawn]

@steve99 has a thread on the switchover process that might be good reading.
http://www.ft86club.com/forums/showthread.php?t=67310

[ZOMFGAARON]

Can you but just a fuel sensor and it run like a flex fuel kit adjusting according to percentages?


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[phrosty]

Originally Posted by zkahle

How so??

E85 requires more fuel to run.

Going from E10 to E85, when you empty your tank and fill up with E85, you're going to probably run around E50-E70 depending on how close to empty you were and your E85 quality. But this is okay -- the result here is that the tune will start rich and quickly lean itself out for the mix. Perfectly safe.

Now the other way. Going from E85 to E10, you're probably running something like E15-E30 on your first tank. So if you flash a 93 tune, it's going to *start off lean*. In closed loop this isn't really a big deal -- you've got STFT and the LTFT will learn quick enough. But there's always going to be an iffy period where you're driving carefully because you're waiting for those LTFTs to build up before you enter open loop.

A flex kit gets rid of this learning period, letting you be much more carefree with your fuel choices.