Running rough on e85

[Twells229]

I seem to have the opposite problem as everyone else who switches to e85 for the first time. I switched tonight, followed the exact instructions. I left my 91 uel tune until fuel trims went way high. Then I re flashed to e85 uel tune. Seems simple enough but after giving the ecu time to learn the new trims and getting the long term fuel trim to level out around -3%, the car is running really rough. It feels like it did when I had the uel without a tune. Felt great on 91 uel tune with oft, but now rough on e85. Also, I never had crickets until I switched to e85. Good lord those things chirp loud.

Sorry for the long post!

TL;DR: switched to e85 with oft, got crickets and runs rough.

[Cal3000]

Before you switched to the E85 tune, how much 91 did you have in your tank?

[saj]

Total'd.

But seriously, a pump may be advertised as "E85" but the ethanol level will be much lower. Be aware of what you're actually putting in your car.

[Twells229]

Originally Posted by saj

Total'd.

But seriously, a pump may be advertised as "E85" but the ethanol level will be much lower. Be aware of what you're actually putting in your car.

That's what I'm thinking since trims are trending negative. I'll give it some more time to adjust and if it stays rough then I'll just go back to 91.

Also, the gas needle was on the red so I assumed I was about to run out but I put in exactly 11.5 gallons of e85 so there must have been two more of 91 in there.

[steve99]

Originally Posted by Twells229

I seem to have the opposite problem as everyone else who switches to e85 for the first time. I switched tonight, followed the exact instructions. I left my 91 uel tune until fuel trims went way high. Then I re flashed to e85 uel tune. Seems simple enough but after giving the ecu time to learn the new trims and getting the long term fuel trim to level out around -3%, the car is running really rough. It feels like it did when I had the uel without a tune. Felt great on 91 uel tune with oft, but now rough on e85. Also, I never had crickets until I switched to e85. Good lord those things chirp loud.

Sorry for the long post!

TL;DR: switched to e85 with oft, got crickets and runs rough.

If your LTFT are only around -3% then the ethanol content is fine.


If it was low ethanol content your LTFT would be -10 or less
If ethanol content was high like 90% then your trims will be positive +5% or more.


Are the fuel trims around 3% over the entire rpm range ?


Take some logs
look for IAM =1
LTFT less than say 7% or so +/-
look at Commanded AFR and AFR(measured)


some cars run pretty rich on E85 on oft tunes.

[JSanders]

The OFT is supposed to be able to run anywhere from E60-E90, which is the tolerance range that is regulated for E85 fuels. If you drive normally without pushing it for maybe 5-6miles after fill ups it should learn itself. I ran it for a couple months and could tell small differences between fill ups.


As for the crickets.... It's long since been determined that the ethanol in fuel caused the crickets... What did you think running 85% ethanol was gonna do... Haha. Learn to love the crickets, they are like your pets now.

[smg1138]

I used to think ethanol caused the crickets, but when I'm on E85 I don't get them. It's only when I'm running E10 that the crickets tend to appear. I honestly think it may have more to do with lubricants in the fuel than anything else.

[Tcoat]

Originally Posted by smg1138

I used to think ethanol caused the crickets, but when I'm on E85 I don't get them. It's only when I'm running E10 that the crickets tend to appear. I honestly think it may have more to do with lubricants in the fuel than anything else.

I am convinced it is the ethanol but only in the smaller percentages.

[JSanders]

I had bad crickets on E85... I switched back to 93 last fill up cause I'm selling the car . Maybe it's because I already had crickets before so it just made it worse. Who knows haha

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