Ethanol In pumps ????

[Longshot270]

Originally Posted by JackandJanet

Ethanol DOES have a higher resistance to pre-ignition, which is what octane ratings are all about, but if the pump says 87 octane, that's its minimum antiknock rating. It COULD be higher, but it won't be less. And, I suppose you could try advancing the timing in small increments (i.e., 0.25) and see what happens.

However, I'm fairly certain the antiknock properties of gasoline are improved through the use of additives in the refining process that contribute to an increase in cost. I don't really see a refiner using those costly additives in the same way if the antiknock properties are improved by adding ethanol. So, I'd guess that the mere fact that gas is E10 has not improved its octane rating.

However, different brands CAN have slightly different octane ratings as long as they meet the minimum shown on the pump. You can experiment to find a brand that will let you advance the timing some. The trouble is, our trucks have anti-knock sensors built in to the system that will actually retard the timing if detonation is detected. So, advancing timing may actually be non-productive.

I know I tried advancing mine once, by 0.25, back when I had an Edge before it was converted to a Gryphon. I immediately noticed an uneven idle. I put the timing right back to "0".

- Jack

The only two or three of the stations serve ethanol as a side dish but I'm still paying $2.57 for regular 87. Suprisingly one of the stations with the 10% ethanol seems to make my $20 last longer than the regular from other stations, and it's not because of the price/volume difference.
I wouldn't change the timing too much but I did get better results on the canned tunes by moving it up to .25 then to .5 degrees. I probably could have gone further but I decided not to.
Jack, my truck is almost the opposite of yours. Before I got my programmer, my truck had a slightly uneven idle. The tunes and advanced idle cleared it up. Ha, that just seems strange to me.