No CEL's!

I finished out this tank of E20 with no CEL's whatsoever.  E20 is stable in this vehicle.  Unfortunately, that is only about 89 octane according to my calculations.

Tank #6

Well, I f-ed up.  I meant to put in 3.5 gallons of E85, and instead I put in $3.50 of E85!  D'Oh!  At least I'm not getting any CEL's, although I think it sounds worse under acceleration (i.e. pre-detonation)


Gallons E85: 2.204 @ $1.589/ gallon


Gallons 87 Octane: 11.536 @ 1.689/ gallon


Ethanol %: 20.06%
Octane: 89.4


Savings per tank over premium @ $2.089/ gallon: $5.72


The car is running well, other than the occasional CEL, no issues.


I'm going on a trip this weekend and will run some premium (93 octane) to see how that compared to my E85 mix.

CEL, CEL, CEL

This tank was BAD.  I got the CEL early and often.  It eventually cleared right before I had to fill up again.


Bottom line is that 4 gallons of E85 in a tank is pushing it.  ~E25 is not stable in this car.


I'll try 3.5 gallons of E85 in my next tank

Tank #5

Gallons E85: 4.020
Price E85: $1.509

Gallons 87: 8.371
price 87: $1.609

tank ethanol %: 27.59
tank octane: 91.13

Savings per tank compared with premium @ 2.009: $5.35

Despite getting a CEL briefly, the car ran well.  I also added some Seafoam to the tank about halfway through to further clean the fuel system.

Got a CEL, cleared itself

Once again at about 3/4 of a tank, I got a CEL.  This time is was P0171 and P0174, both lean conditions related to too much E85, I believe.

After a few miles, the CEL cleared.  I'm not sure what is actually going on except that E25 is borderline for this vehicle.

Tank #4

Gallons E85: 4.020
Price E85: $1.409

Gallons 87: 8.866
price 87: $1.509

tank ethanol %: 26.6
tank octane: 90.89

Savings per tank compared with premium @ 1.909: $5.56

NO CEL SO FAR!

Car is driving great.  Drivability on E25 is excellent.

CEL cleared itself

The check engine light turned off itself about 50 miles after it came on, same tank of fuel.  It must have been an anomaly.

Just to be sure, when the tank was empty, I put in 5 gallons of 87 and ran that to empty.

My observation on running on straight 87 octane gasoline (10% ethanol) is that the engine runs about the same, but I did notice some knocking under hard acceleration.  It is not something you notice on ~90 octane ~E25.  The car accelerates very smoothly and quietly on E25.

I have the scanguage II, I'm looking at ignition timing, and I did not notice any change in timing from E25 to E10 and back.  The ECU should be changing timing in order to deal with the lower octane rating of E10, but it is not noticeable at the frequency that the scangauge monitors ignition timing.