I plan on swithcing to e85 soon. I'm on a tight budget. And I prefer to get one e85 tune instead of getting tuned once in the summer and once in the winter. Which season is the best for safety so when the e85 blend changes, my car is still safe?

 

I have not seen a large difference in output from E70 to E85.

I would get tuned on E70 and just make sure the AFR is correct / has room to lean out when E85 is in season, and would keep tabs on fuel trims as they will swing positive when you go from E70 to E85.

We are lucky in California in that we don't get mixture changes, it's always E83+

I guess that makes up for having to deal with 91 for so long.

- Bryan

 

thanks bryan...id take warm cali weather with e83+ and 91 then what we get in chicago: 93 (or atleast that's what they say haha) and e70+

 

Awesome question!

So do you recommend the same for those of us here in Arizona? I'm not sure of the E85 content differences from Phoenix to Tucson. My plight is a bit different as I'll be E85-tuned in San Antonion and then bring my car here to southern Arizona. Assuming that it's E83+ in Texas, how should I tell my tuner to "tune" for the lesser rating as I want to make sure that my engine stays safe and trying to squeeze every single whp is not more important in my opinion? Thanks.

 

pure_evo, here in Dallas we're seeing E76-E84 during this winter. If you're moving around I'd recommend thinking about getting an ECA installed.

Bryan@GST: I'm still dialing in my injectors a bit, but I am seeing more knock the lower the ethanol content goes. I'm also seeing fairly large WOT swings in AFR between E79 and E83/4 (like .5 on the gas scale) -- I have LTFTs disabled for WOT. Part of that is being tuned kind of on the edge. Once I get the injectors dialed in I'll retune and see what it does.

 

Crap... I really didn't want to hear that. OK. Assuming that I purchase an ECA, how do or would I make changes to my tune (if that's what I have to do)? For example, I'm tuned on E84 and then I get a tank of E70. Would it be possible to simply get a conservative E84 tune to compensate for the lesser quality as season pass?

 

It depends on how aggressive your tune is. But you can just turn down the timing and the boost a bit and likely be fine (similar to going from a 93 to a 91 map).

There are a lot of people that go through the seasonal changes without changing their maps though. They likely aren't driving super aggressively in winter though so keep that in mind.

 

OK. This is good information to know and apply. Thanks.