Hi all,
I have been interested in running my car on E85 for a while now and I finally decided it was time to give it a try.

So, here’s what I did to make my 99 WS6 Formula run on E85. With the exception of a lid and a K&N air filter, the car is stock. 75,000 miles on the odometer.

Note that this is what has worked for me. It might not work for you, so don't blame me if you mess up your car.


1: First, I replaced the stock 26# injectors with 42# injectors. I used the Delphi/Lucas 42# injectors which are rated at 48.83# @ 58psi.


2: I then scaled the Flow Rate vs KPA (IFR) table for the new injectors. I did this by scaling my current IFR numbers by 1.8486. Type 1.8486 in the lb/hr field, high-light all the table entries, and hit the ‘X’.

The 1.8486 value was calculated using the following formula:

(New Flow Rate) / (Old Flow Rate) = (48.83) / (26.41431) = 1.8486…

See the attached original IFR table (IFR_original.JPG).
See the attached updated IFR table (IFR_updated.JPG).

Note that if your stock injectors are 28#, the multiplication factor should not be 1.8486, but rather something close to 1.701. The point is to end up with an IFR table that reflects the flow rate of the new injectors at 58psi.


3: Next I reduced the “Injector Offset vs. Battery Voltage vs. KPA VAC” table by 12%. The reason I did this is that the Delphi/Lucas Injectors apparently have a quicker “reaction time” compared to our stockers. I picked the 12% value based on reading the ls1Tech and hptuners forums.

To reduce the table by 12%, I typed 0.88 in the msec field, high-lighted all the table entries and hit the ‘X’.


4: I then flashed the ECM with the updated IFR and Offset tables, and started the car (still with only gasoline in the tank). I let it idle for a while and took it for a 5 mile test drive. No idling problems, no surging, no popping in the exhaust on decel. It felt great.


5: Next, it was time to try running with some ethanol. I put 5 gallons of E85 with the approx. 2 gallons of 93 octane gasoline I had left in the tank. That put me at approximately 70% E85, which again means roughly 60% ethanol.

Based on the Stoich AFR table from an ‘04 Flex Fuel Tahoe, I updated my Stoich AFR field to 11, re-flashed the ECM and went for a drive. It drove fine.

See the attached Flex Fuel Stoich table (tahoe_flex_fuel.JPG).

See the attached Stoich setting for 70 percent E85 (stoich_70percentE85.JPG).

Note that HPT re-calculated the Stoich AFR to 11.01075.


6: Next, I filled the tank all the way up with E85. Having approximately 2 gallons of regular gas in the tank, it put me around 75% ethanol. Again, based on the ’04 Flex Fuel Tahoe table, I set the Stoich to 10.2 (HPT re-calculated to 10.18905), and re-flashed. Once again, the car ran great.


7: I drove around with the 10.2 Stoich setting for 200 miles or so, until the tank was almost empty, filled up with E85 again and set the Stoich to 9.765 (HPT re-calculated to 9.77566).

See the attached Stoich setting for 100 percent E85 (stoich_100percentE85.JPG).



Conclusion: I have only driven a few hundred miles with E85 so far, but the car is running great. I can probably benefit from some more tuning (I did notice my LTFT are “elevated” after driving for a while and then idling), but using the SOTP "dyno" it feels like I now have more power on the low end, and I have no driveability issues so far.

It is the middle of summer here in Texas, so cold-starts have not been a problem. We'll see how it goes later in the year, if we get temps in the 40s and 30s.

If I run into any problems (like “don’t use ethanol, it will eat your fuel lines and rails” kinda problems), I will post up. Also, I am monitoring my mpg, and from what I can tell so far, the “in-town” mpg has dropped 10-15%. I haven’t had a chance to get on the highway yet.

 

Have you played with timing at all?
I would think most of the extra power available from E85 would be through its higher octane rating thus allowing for a higher threshold for detonation, allowing for more spark advance.

 

Unless you are pushing into open loop near/at WOT you will be in closed loop control.
Higher ltft probably suggests your ve/ifr etc is out a bit.
Time to get a wideband on the job to dial in your openloop

 

Bad ***, glad to see some Austinites taking advantage of the E85 pumps. I am thinking about using E85 mainly for the octane rating, just for safety sake on my setup.

Gonna dyno it sometime?

 

Ah man, I so want to do this with my truck, but the closest E-85 pump to me is 60 miles away. I've thought about building a bunch of tunes for the approx ethanol percentage I have and use the stand alone flashing of my EFILive V2 ( when ever the firmware comes out ) and fill up with E-85 when ever I can. I wish more people would take the plunge.

 

I also want to do this with my TA. Still trying to decide if the change in mileage and price per gallon is worth it or not. Also, is it possible to use EFILive to somehow make a tune that runs on E85 and Premium mixtures both? Similar to how flex vehicles work. I would think you would need two .tun files and reflash whenever you switched from 100% E85 back to 100% gas.

 

That's badass man! E85 and Ethanol has always intrigued me! It's a shame there's only one E85 pump in Austin. I'll be getting my T/A in a week or so, and I've been researching and throwing around the idea of running E85. It's nice to know that it can be done, and you're local (so you can help me ) Good luck, Definatly keep us posted!

 

This is what I was thinking about, have 4-6 tunes loaded in my V2 with different stoich numbers and timing depending on the approx ethanol I have in the tank, then I can just flash in the tune that best matches the % I'm running.

I think you could make a kind of "in the middle" tune, to run either and let the LTFT pick up the slack, but would have to be VERY conservative and probable not worth it.

 

Many of the HEB pumps are E85 equipped now...