Military-Vehicles: Re: [MV] What about oxygenated fuel?

Re: [MV] What about oxygenated fuel?

John Galt (
Sun, 12 Oct 1997 22:07:48 -0400

Alan Bowes wrote:
> snip...
> This is required in certain U.S. metropolitan areas (some 35 or 40 areas, I
> believe) during winter months, when temperature inversions tend to concentrate
> CO and other emissions, when engines tend to run richer for a larger percentage
> of the time due to the lower temperatures, and when more fossil fuels are being
> burned
> for heating purposes.
> snip...


Why would engine run richer when the weather is colder? Colder air
is more dense, therefore I would expect the engine to be running leaner
during the Winter than the Summer, therefore have less of a CO problem
(once at operating temperature).

Am I missing something?

I still don't really understand why, when considering modern cars with
fuel injection and exhaust gas oxygen sensors, why they even bother
with oxygenated fuels since feedback systems within the cars (mass air
sensors on intake air, etc) keep them burning properly regardless of
environment. It is only owners of "antique" vehicles (like members
of this group) who see "cleaner" exhaust through use of these Winter
fuels (albeit at the expense of soft fuel system parts).


Darren Allen

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