Using E85 with OFT with new 51% minimums
 

I just fueled again and noticed at the second gas station that the new minimum for E85 is now 51%. That is below the 60% threshold set on the E85 tune. Does this mean we need to have a more conservative tune or most of those that have the Ethanol sensors finding the pumps are above 60%?

John

I have run those tunes down to E40 or less without too many issues, it does depend on the quality of the petrol they are mixing with the ethanol though

just keep an eye out for knock ie see if your IAM drops below 1 and see what your fuel trims are like.

If the IAM does not drop below 1 and the fuel trims dont get anywhere near +/- 20% (the max trim is 30%) then you should be pretty good.

on low E% fuel i would expect the trims to go negative (ecu reducing injection times as a result of petrol content), i would not expect trims higher than -10% or so.



you could adjust the port injector scaling and DI pressure multipliers to bring the trims back and remove a bit of timing if you get knock but I don't think it will be a problem unless the petrol they are using is really crap on an NA tune

My ltft are ranging from -6 to -18. I suspect this batch is above 60%. I am inexperienced in modifying maps. If I see the IAM drop below 1, I will go back to the 93 map.

John

If your always going to be on low e% e85 then you could rescale your maf sensor to suit and bring those fuel trims back below 10%

The check for knock and pull some timing out of the base timing B map in the problem areas if your seeing the IAM drop below 1, or consistently seeing knock over -1 correction in an area.

I've been running it for about 8 months now at a 51% minimum station

I just went back to the 93 tune. My stft went to 25% telling me the e85 left in the lines was pretty close to 85% ethanol. After about 50 miles, and he ltft has stabilized around 3%. I just am not willing to risk damaging my engine. I wish Shiv would come up with a flex fuel system.

John

Its possible in the future a guy in OZ is looking into writing opensourse flex fuel code for ecu.
You would still have to buy and install flex sensor\kit into fuel lines and connect input to ecu via evap purge solenoid or rear o2 sensor. flex kits about $600 or so plis install although diy is fairly simple.

I would email shi re caacity of current tunes to cope with lowe e content he may put out some mods


my suggestion would be
Re do your maf scaling on a average batch of the e85 available in your area
this will get your fuel trims low and your fueling correct.

even on 50% e its still going to have suffient octanne rating to run the current map
monitor for any knock you may get a bit arround 2000-3000 rpm

pull a bit of timing in the area if you see knock

to give yourself some extra insurance

take 4 degrees of timing out of the base A and B maps and put this 4 degrees into the Knock Correction max A map. Your overall timing will be the same but the IAM will now have much more scope to reduce timing if the iam ever drops below 1