DIY E85 Conversion

This thread is NOT about the feasability of running E85 in our cars, nor is it about the politics of E85. It's not even about optimal tuning for E85. Please keep it to the fuel conversion itself. Thanks.

 

 

Disclaimer: I've done this just once on my own car. I am not a mechanic or a tuner. There are probably other good ways of doing this, but this worked nicely and is pretty easy. Be patient and safe at every step. Check your logger and logs.

 

Prerequisites:

 

· Hardware: upgraded injectors, upgraded fuel pump, WB02, laptop, Tactrix cable

· Software: RomRaider (use lambda fuel definitions), EcuFlash, Learning View, configure WBO2 to display lambda

· Tune: Good gas tune with nicely scaled MAF and injectors. LTFT's should be near zero.

· Knowledge/Experience: Experience with software, ability to analyze logs

· E85!

 

 

1. Make 2 changes to your existing map. Both changes add 30% more fuel. Yes, that's it for the changes and you now have an E85 map. It's not optimized yet, but that's it for the conversion itself.

a) Multiply existing injector scalar by 0.6975

b) Multiply tip-in table by 1.3. (EDIT 9-25-09: This suggestion is theoretical, based upon suggestions in the NASIOC FAQ. I haven't seen evidence to suggest this is an absolute and other multipliers may work better, worse, or the same. It is what I did and has worked well for me.)

 

2. Arrive at gas station with a half gallon or less of straight gas in the tank. Bring laptop, new map, and Tactrix cable.

 

3. Add 2 gallons of E85. Flash new map.

 

4. Start your logger. Start engine. (It should start with a rough idle for a couple seconds and then smooth out pretty nicely.)

 

5. Sit and watch STFT's and LTFT's on logger for 5-10 minutes. They'll probably probably go negative due to the straight gas still in the tank. That's fine.

 

6. Once Learning A has stabilized, take the car out for a spin. Keep the throttle position light and steady to begin setting up Learning B, C, and D. Plan on driving for 10-20 minutes or so and try to very slowly accelerate to 70mph or so a couple times. Return to gas station.

 

7. Check Learning A-D. Expect negative numbers but they shouldn’t be pegged at -15. If numbers look good and car has felt good and driveable, fill up with E85.

 

8. Continue driving with light throttle. Avoid going WOT until CL is nicely dialed in.

 

9. Adjust injector scalar as necessary to get LTFT's about where they were prior to E85 (around zero).

 

10. Do a 3rd gear pull to 3500rpm. WOT AFR's should be 0.76-0.78 for now. Continue logging and increasing the pulls by 500rpm ensuring that AFR's are within the WOT target range of 0.74-0.78.

 

11. Drive as usual for a few days. Try to get all types of driving in. Using Learning View, check LTFT's to ensure still near zero. Do another 3rd gear log, again ensure that WOT AFR's are around 0.76-0.78.

 

12. Tune for E85 - here's my thread.

Nice write up, now I just need some E85.

Nice write up, now I just need some E85.

 

 

You E85 guys make me sad.

You E85 guys make me sad.

why...because you need bigger injectors?

 

 

 

:lol:

isn't the fuel system not designed for E85? Specifically the fuel lines and such?

why...because you need bigger injectors?

 

 

 

:lol:

 

I know, I am allergic to them. Had em in my hand, then got rid of them! Eeeeuuuuuuuuuuuwwwwwwwwww.

 

 

Too bad I can't do a FR TS 3071 on stock injectors (even w/ alky).

isn't the fuel system not designed for E85? Specifically the fuel lines and such?

 

That's a good question, of course. The answer is that E85 can be run just fine. See the 64-page FAQ on NASIOC for details.

Interesting, good luck!

I want to see how much better you run at Bandimere with your E85 tune. I am going out on 7/16, interested?

 

Where are you finding E85 at? I saw a link for the stations somewhere but cannot find it again.

 

Edit: Quick google search found the stations.

I doubt I'll be done tuning by 7/16. I'm still at steps 9-11 above, actually, but I haven't had any time to get logs, etc. Hopefully I'll be ready to start tuning tomorrow.

 

My guess is that I'll gain 0.2-0.3 seconds and 2-3mph on the traps. My prior best is 14.09 at 99.8mph (5800ft). I hope to catch up to The Fastest Outback and match his 13.77. I don't know how much my E85 gains will show up in the quarter mile since the bulk of the improvement seems to be 2000-4000rpm and less than a second of a quarter mile run is spent under 4krpm.

 

I'll begin the tuning phase the next day or so.

this should be good

My guess is that I'll gain 0.2-0.3 seconds and 2-3mph on the traps.

 

After doing some runs at the dragstrip I gained 0.55 seconds and 2.3mph.

 

Just reviewing this thread any making some updates to the original post, figure I'd update the performance gains here too (although I already did on the tune thread).

b) Multiply tip-in table by 1.3.

 

Why do you do this? I assume you came to this number because, naturally, you need 30% more fuel when running E85. You know who is tuning my car, and he did not adjust tip-in between my 93 octane and E85 maps. Should I hit him ?

 

My WB is far back in the stream, so its hard to log AFRs when quick changes are being made... there is a delay in the reading, and the turbulence back there does not help either. I cannot really tell if I am a little lean when I first hit the pedal (which would be the case, correct)?

 

Here is my current E85 tip-in:

0.00     0.98     1.95     3.91     5.86     7.81     9.77     11.70    13.70    15.60    17.60    19.50    21.50    23.40    25.40    27.30    29.30    31.30
0.000    0.132    0.200    0.264    0.396    0.596    0.728    0.792    0.924    1.056    1.256    1.520    1.664    1.788    1.972    2.156    2.336    2.520

Why do you do this? I assume you came to this number because, naturally, you need 30% more fuel when running E85. You know who is tuning my car, and he did not adjust tip-in between my 93 octane and E85 maps.

 

Yes, that's why. However, I'm not 100% sure this should be done so I will edit my write-up above. Yep, it's tough to measure real transient changes in AFR and this suggestion was more theoretical (based largely upon what I had read in the NASIOC FAQ) than empirical.

 

Both too much and too little fuel can be dangerous here, but the transition is so fast and E85 is so forgiving there is probably a wide margin of error. At least if you are too lean you'd knock and get feedback.. I'd hate to be way too rich and washing the cylinder walls.

 

I'm sure there are some tuners on the romraider forums that can give us a more definitive answer and perhaps the groupthink on this has changed since my write-up.

 

At any rate, I'm pretty sure that I did exactly that on my E85 tune and I've been daily-driving it for 16 months with that tip-in strategy and no issues.

I just increased mine 15% to see what that would do. I am not sure how its supposed to "feel" like when I tip in quickly. I will try to log some parameters and purposefully get in and out of throttle to see if I am going lean or rich just after the tip-in. I still don't know if I will be able to determine anything from the feedback, because I am not sure what it is supposed to look like.

 

I also made the tip-in more linear from 0% to 30%, though I highly doubt this makes a difference.

 

I have no idea how to judge how well my tip-in is defined. Right now I will say that I get a slight buck when I tip in hard, but I have no idea if I am rich or lean. My WB is too far back to pick it up cleanly.

For tip-in, log the front OEM O2 sensor.

 

Change your targets in the pri fuel table to something richer then the value in the min pri active OL enrichment table. Then log AFR and you don't have to worry about AFR corrections skewing things.

I know this thread is old, but I would like to say, 6 months ago, I decided I didn't give a damn what anyone said, I wanted to try e85 without a conversion in my 2006 Nissan 350z GT. So.. that being said, I could have been making a terrible move, but I ran 5-6 tanks full of e85 in my car without changing a single thing, and the only thing that ever showed up was my 02 sensor kicking on the CEL. I only stopped running e85 in case it would ever act up. I drove the car for another 5 months and traded it off, still running smooth as could be.