Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 6/7/83; site hao.UUCP
Path: utzoo!linus!decvax!harpo!seismo!hao!band
From: band@hao.UUCP (Peter Bandurian)
Newsgroups: net.auto
Subject: a wierd problem
Message-ID: <750@hao.UUCP>
Date: Thu, 1-Dec-83 17:04:23 EST
Article-I.D.: hao.750
Posted: Thu Dec  1 17:04:23 1983
Date-Received: Sun, 4-Dec-83 03:51:24 EST
Organization: High Altitude Obs./NCAR, Boulder CO
Lines: 46


	Here is a wierd problem.

	I keep track of the fuel mileage any car I have as a matter
	of course.  I do this not so much because it is interesting in
	itself but because it is an indicator of when something may need
	maintence or repair.  Last winter I noticed that the Rabbit's fuel
	mileage started dropping.  Actually it varied wildly, from the
	accustomed 30mpg to a low of 21 mpg.

	I have a 1976 Rabbit with a carburated engine and a Heathkit
	capacitive discharge system.  I looked for a possible cause.  I played
	with the timing.  I played with the carburation.  I tried different
	brands of gasoline (supposedly, the majors make better gasoline than
	the minors), super as well as regular (unleaded).  I tried BG
	Supercharge (the theory was that with 99,200 miles on it a little
	cleaning up would not hurt; the VW dealer's idea; it didn't help).
	I tried octane booster. The choke was okay.  I replaced all the
	rotted little rubber vacuum hoses.  I checked the temperature
	controlled vacuum valves of which there are many in this vintage.
	The anti-backfire valve, the by-pass valve, the by-pass by-pass(!)
	valve.  I replaced the thermostat (the old one turned out to be
	marginal but certainly not bad).  I even tried ignoring it.  Nothing
	helped.

	By Spring I noticed a correlation between fuel mileage and average
	ambient outdoor temperature.  A normal winter in Boulder, Colo. has
	a tremendous temperature variation: from warm, spring-like to, well,
	winter.  Sometimes all in one day.  The colder it got, the
	worse the fuel mileage.  If it warmed up, up went the mileage.  Like a
	yo-yo.  Like Boulder's weather.

	Well it's doing it again this very snowy Fall.  The only thing I
	learned this summer is the mileage stayed consistently around 27
	(compared to the former 30mpg).

	I realize a small mileage loss in winter is normal: the first two
	winters with this car saw a 10% mileage drop (ie 30 -> 28mpg); but
	nothing like this.

	Anyone have any ideas?

			Peter Bandurian
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