OFT E85 Fuel Trims?

[loki86]

I've been running the OFT e85 shelf tune for some time now and noticed my LTFT are always a little high at idle, hovering anywhere from +7% to 11% while on throttle it seems to be fine. Indicative of a possible leak, I've checked and found no issues, and switching to petrol tune the trims are perfect (0% at idle, never beyond +- 5).

When on e85 and coming to a braking stop, my car nearly stalls where rpms drop to ~600. Yesterday on a hot day and AC on, the car finally did stall. I also got a p0301 misfire CEL at some point. My fuel trims were hovering around 9% idle during this time.

Would anyone know why this is the case and what I can look into? Obv answer would be checking for leaks, but like I said exhaust components seemed fine and trims were good on regular petrol.

[lightning]

The fuel trims could be because of a difference in ethanol content between what your fuel is and whatever the shelf tune assumes. The p0301 and stalling sounds like a separate problem. Or are saying that switching to the petrol tune stopped the stalling?

[DarkSunrise]

My idle fuel trims with OFT e85 tune are around 9-11 percent. The engine definitely needs the extra fuel to idle. If I flash a new tune, it’ll want to stall at idle until the fuel trims rise to compensate. My guess is it’s due to high ethanol content in the local e85 supply.

My open loop AFR’s look spot on around +5 percent ltft. I’m guessing if I had a full catless header/exhaust setup, I’d need right around 9-11 percent ltft (which would match idle).

Are you using oem header and exhaust?

Also my engine has never stalled out or thrown a p0301 misfire code, so I think that m get be due to something else (like your coilpack or spark plug).

[steve99]

Increase maf scale 5% or so at low end
increase idle rpm especialky on auto to 750


P0301 is likely coil pack

[kevinn711]

Originally Posted by loki86

I've been running the OFT e85 shelf tune for some time now and noticed my LTFT are always a little high at idle, hovering anywhere from +7% to 11% while on throttle it seems to be fine. Indicative of a possible leak, I've checked and found no issues, and switching to petrol tune the trims are perfect (0% at idle, never beyond +- 5).

When on e85 and coming to a braking stop, my car nearly stalls where rpms drop to ~600. Yesterday on a hot day and AC on, the car finally did stall. I also got a p0301 misfire CEL at some point. My fuel trims were hovering around 9% idle during this time.

Would anyone know why this is the case and what I can look into? Obv answer would be checking for leaks, but like I said exhaust components seemed fine and trims were good on regular petrol.

Hey did you ever fix this issue??? I have the same exact problem.....

[Sam86]

Originally Posted by kevinn711

Hey did you ever fix this issue??? I have the same exact problem.....

Same, I never had this problem until I switched to a richer tune. Then I switched back to the previous tune I was fine on and am still experiencing the idle drop.
May just be the tune adjusting I just don’t remember that happening when I flashed the same tune for the first time.

If the issue persists, I’ve seen some people recommend cleaning your throttle body to fix the idle dips on braking. Apparently a dirty throttle body is common even on stock cars below 2016 model year
My idle dropped as low at 430 RPM when coming to a stop right after retuning. Then it’ll go back up and hover around 720-750 in drive and 900-1000 in park.

Tune has been adjusting for about 90kms and it hasn’t dropped as low as 450 again but it still goes very quiet coming to a stop and dips to around 600 for a second