Ten per cent ethanol

My 92 Explorer has chronically been fussy about starting. We have blamed various brands of gasoline as well as things like winter/summer blends and off brand stations.

The symptom has been that a cold engine took two tries before it would fire up. experiments like waiting with the key in the run position, changing air filter, cleaning IAC, etc. have shown no difference. Problem might go away for a while but always returned.

Recently I filled up with an off-brand that was a few cents cheaper and the SUV started nicely every time. At the second fill up at the same station, I noticed a sticker on the pump that advised that he fuel contained 10 % ethanol.

My limited search on the internet found that the ethanol raised the octane rating of the gas. There was nothing I could find regarding starting effects. I understand that the higher the octane, the harder it is to ignite the fuel air mixture. This is why higher octane gas inhibits engine knock. This makes it counter intuitive that the ethanol would enhance starting. It ought to make it harder to start. The 92 service manual when addressing hard starting complaints advises that the use of higher octane fuels may be the cause and that the user is advised to stick with 87 octane.

So what I have is a contradiction. ethanol, raising the octane should make starting more difficult. In practice it almost seems as if the ethanol acts like a starting fluid.

What is the experience of other users, especially those with the older 6 cylinder engines?

Charlie

Reply to
Charlie Bress
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I have had similar variations in starting ability that sometimes seem related to the gas being used. As to the question of octane and the relationship to ethanol... There is more to gasoline properties then the octane rating. There is also the volatility of the gasoline. From info I've read in the past, if you are just dealing with gasoline and comparing an 87 to a 92 octane GAS, the 92 octane will not be quite as volatile and will consequently the vehicle will be a little harder to start. But, when you throw some alcohol in you raise the octane rating even though it doesn't necessarily change the volatility of the gas. So an gasohol won't necessarily act like "high octane" gas even though it has a higher octane.

Reply to
Ashton Crusher

But is the ethanol acting like a starting fluid because it is more volatile than gasoline?

Charlie

Reply to
Charlie Bress

Interesting question. I always thought starting fluid was much more volatile then alcohol. I thought they used ether for starting fluid.

Reply to
Ashton Crusher

Ethanol does raise the octane rating a bit, but is less volatile than gasoline. So the 10% ethanol mix will be lower in volatility but higher in octane. But in addition, the ethanol acts as a dry gas--it absorbs any water(from condensation etc.) that is in your gas tank. This alone may make an engine start better in hot as well as in cold weather. In my area (New York) the 10% ethanol mix is the only thing allowed to be sold for about half of the year in order to meet emissions requirements. So my Mountaineer V6 only gets that and has never had a starting problem.

Ken

Charlie Bress wrote:

Reply to
Kenneth J. Harris

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