On 4/30/05 17:22, "Robert Fisher" <refisher@MCHSI.COM> wrote:

> 
> The idea that refineries formulate gas for various elevations strikes me as
> impractical, inefficient and unlikely, but I don't refine gas so what do I
> know. However, I have bought gas in Needles (which I don't recommend, get it
> in Kingman if you can) and driven to Flagstaff (roughly 6000 ft. difference)
> in a few different vehicles and I've never noticed an elevation effect.

The answer is yes they do.

Here in colorado it is possible to get different blends according to the
altitude.  But that blending is for emissions and your engine should run the
same either way if the O2 and AFM and ECU are working correctly.

With my van when it was aircooled I would occassionally run into starting
over rich at higher altitudes (above about 7500 foot) in cold weather.
Usually ether took care of the problem for me.

After I did a thorough injector cleaning and reset of the timing, the
problem dissappeared. I forget how much advance I added but it wasn�t much.
I thought I found that high altitude timing info in this groups archives but
may be wrong.
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jimt
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