[s-cars] A/C AND gas milege
Matthew Russell
MatthewR at greenhosp.org
Thu Jun 27 12:06:05 EDT 2002
Bruce, Taka, et all-
my .02 on the AC, power, and milege issues... (BTW, that sounds like a fun
little test!)
Just got back from an 1800 mile trip, and I kept track of milege manually to
do a comparo with what the trip computer says in my '92.
The computer gave an accurate mpg only once out of 4 tanks, otherwise it
calculated between 3/4 and 1 mpg OVER the actual mpg that I calculated based
on gallons put in the tank and miles driven. Now who knows if my odometer
is close to being accurate...
The other thing I noticed is that with the AC on, you lose about 1 mpg
overall on the highway, based on ~420 miles per tank. RE: the recent
discussion gas milege, I replaced my o2 sensor and cleared the codes the day
before we left. I also put in a t-stat within last 6 months. Before the
t-stat, I was seeing 21-22 mpg highway, that jumped to 24 before the o2
sensor failed, after which it fell and rose again after the o2 replacement.
Now I recall seeing a post awhile back that upon full throttle acceleration,
the AC compressor should kick out and then resume on normal throttle
position. I have felt my car do this several times, but not recently.
Taka & Bruce- is it possible that the kick out is not working on one of your
cars as well?
also, maybe one of your cars has a greater freon charge than the other? I
think a low ac charge will cause the compressor to cycle constantly as
opposed to kicking on/off...
HTH,
-Matt 92 s4
Message: 6
Date: Wed, 26 Jun 2002 22:58:09 -0400
With A/C on in both cars, I pull
away slightly as the RPMs increase, sort of a steady pull. Same test with
Taka turning off his A/C, and the cars are dead even.
So that tells me maybe A/C saps more than 5HP?
Bruce
Matthew Russell
technical specialist, Lab Outreach
(203) 863-3396
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