Ethanol In pumps ????

[Jackpine]

Originally Posted by Dfishrmn

Just to revive this issue! All the stations here are pumping gas with 10% ethanol now. Does this affect our tunes? I have heard that ethanol has a higher octane rating than pure gas. Should the timing be advanced or rewritten into the code?

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