Thread: E85 and flex fuel setup

I will be converting over to E85 this weekend and need a few things cleared up about some of the setting for the nismotronicSA. Under the flex fuel section, does this need to be enabled and a fuel composition sensor installed for the car to operate optimally? This seems like it would be ideal if I were going back and forth from 93 to E85. However, from what I understand, the levels of ethanol can vary depending on geographical location and seasons. Would it be best to play it safe and install the fuel comp sensor incase I get an off batch of E85?

Setup:
USDM 99 SR
18g turbo
rc1000 injectors
Aeromotive AFPR
High flow fuel rail
Walbro 255
MAP conversion
Elec boost solenoid to be installed monday
Max boost will be around 18-20psi

I have everything aside from the composition sensor and I do not think I need it, but its kinda a gamble not knowing the actual alcohol content.

I actually answer this question on a weekly basis up here when the weather starts to get colder.

The fluctuation from E85 to E70 in the winter months will simply cause the car to run on the rich side and for MOST it will not have any ill affects and you can simply run the exact same tune you ran on E85 on E70.

Now, going the other way (from E70 to E85) the car will run a bit leaner. So just take notice to your AFRs when the weather starts to warm up and check the ethanol content in early spring to see when the stations start to switch back over to E85.

But, the best and most accurate way of doing things is to definitely run a ethanol content analyzer and run the 0-5v output from that to the ECU so you can use the built in flex fuel corrections.

Although, it isn't absolutely necessary to do it that way .. it will provide the best results!

10-4. Thanks for the input. Makes me feel better about tackling this. I'm going to order the analyzer to be safe. I don't plan on bouncing back and forth between 93 and E85, should I just avoid setting up the flex fuel option?

Any advice you can give before I start this? Tips, tricks, maybe something nismotronic specific?

Update: all done. This is stupidly simple. With 1000cc injectors, I dropped the fuel value to 700 and decrease the over map values by 5 just for wiggle room. That's it. As long as you have a good tune, simple adjust the fuel value.

Glad to hear you got it sorted. It really is that simple

Just keep an eye on your AFR after your first tank of E85 to make sure you didn't have a diluted batch in the first tank.

I ran her around the neighborhood until she started bucking under load. Put 5gl in, set my afrs, then drive her up to the store for a top off. Getting about 26mpg. Really surprised the hell out of me. Also hitting 12lb at 3k. Just nuts.

I've got to try this. Are you worried about the tank rusting or old lines deteriorating? That's the only thing that has been stopping me, at this point I think I'm just going to switch.

The tank will not rust. I've been on it for over 2 years with 0 issues. My tank is clean inside. You can change the hoses if you want to but you should be ok. It's not like methonal. Most gasolines out there have ethanol in them.

Kevwal is correct. E85 is no more corrosive than 93 octane. I've done so much research on this and basically what it comes down to is in the late 80's - early 90's, E10 was starting in production. Auto makers started to use ethanol compatible fuel lines and rubber. The only reason I would ever suggest running new lines is if you are pushing more than 400hp as you will max out the flow rate of the factory lines.

So in the case that I am making 400+ I should run stainless braided lines from the tank to the rail? I can see how the stock hard lines on the car could be restricting with the amount of flow I will need for E85. I have AN -6 running from the hard lines on the firewall to the rail and FPR with an inline filter, is that not sufficient for 400+? I was thinking my walbro 255 would be my weakest point.

Also curious about the wideband. Do I need to go into the settings and switch the fuel to E85? Or will it read properly without changing anything? What AFRs do I tune for?