YACT: Sharp Drop in Gas Mileage

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D

Dedpuhl

Lifer
Nov 20, 1999
10,370
0
76
I have a 2000 Hyundai Tiburon (plz, no Hyundai jokes/slams/disses/etc) and brought my car in for maintenance a couple weeks ago. The a/c compressor was bad so they replaced it.

Before I brought the vehicle in, my odometer would always reach around 290 miles before I would need to get gas (there would still be one gallon left in the tank). Since the repair work, I've been having to fill up when it barely reaches 250 miles.

What could cause such a drastic drop? I just thought I'd get a professional ATOT diagnosis before I bring it to the shop this week. :)
 
N

no0b

Diamond Member
Jul 23, 2001
3,804
1
0
are you filling up at the same gasstation at a non sloped pump?
 
D

Dedpuhl

Lifer
Nov 20, 1999
10,370
0
76
AFAIK, the only work was done on the A/C. My a/c use has actually decreased b/c of the change in weather.

Also, I have a 12 gallon tank.
 
D

Dedpuhl

Lifer
Nov 20, 1999
10,370
0
76
Originally posted by: no0b
are you filling up at the same gasstation at a non sloped pump?
Click to expand...

I've filled up 3 times at 2 different places. They are the same places I usually get gas.

There was talk a while back about the EPA forcing this area to use reformulated gasoline, but it has been put on hold. So, I think the gas is the same. (I use mid-grade - 89). If reformulated gas is used, the business is required to put a notice at the pumps.
 
Colt45

Colt45

Lifer
Apr 18, 2001
19,720
1
0
Did the mechanic 'fix' it by jamming the clutch so that the compressor is always on? ;)

i think youre probably just imagining shit.. or something.
 
D

Dedpuhl

Lifer
Nov 20, 1999
10,370
0
76
Nah I think they replaced it. It was warranty work at a Hyundai dealer.

I always monitor my gas usage, so I can't be imagining anything.
 
I

ItTheCow

Senior member
Apr 7, 2002
365
0
0
It might be the gas. It seems to always happen with my car during the winter season. I always seem to get a few less MPG. I believe they put in some sort additive to help prevent gas from freezing in your tank.
 
CrackRabbit

CrackRabbit

Lifer
Mar 30, 2001
16,642
62
91
Originally posted by: ItTheCow
It might be the gas. It seems to always happen with my car during the winter season. I always seem to get a few less MPG. I believe they put in some sort additive to help prevent gas from freezing in your tank.
Click to expand...

Ding Ding Ding!!! We have a Winner!
 
E

eelw

Lifer
Dec 4, 1999
10,053
5,158
136
Yes, I know it should not cause a 15-20% decrease in fuel economy, but check the tire pressure. It could account for almost 10% of your loss. The other 10% could be accounted for the cooler fall temperatures.
 
AgaBoogaBoo

AgaBoogaBoo

Lifer
Feb 16, 2003
26,108
5
81
Originally posted by: CrackRabbit
Originally posted by: ItTheCow
It might be the gas. It seems to always happen with my car during the winter season. I always seem to get a few less MPG. I believe they put in some sort additive to help prevent gas from freezing in your tank.
Click to expand...

Ding Ding Ding!!! We have a Winner!
Click to expand...

wtf?
 
D

Dedpuhl

Lifer
Nov 20, 1999
10,370
0
76
Originally posted by: CrackRabbit
Originally posted by: ItTheCow
It might be the gas. It seems to always happen with my car during the winter season. I always seem to get a few less MPG. I believe they put in some sort additive to help prevent gas from freezing in your tank.
Click to expand...

Ding Ding Ding!!! We have a Winner!
Click to expand...

never noticed it before in Baton Rouge...
 
db

db

Lifer
Dec 6, 1999
10,575
292
126
Do you have same amount of power or less? Noticed any other changes?
 
L

lobadobadingdong

Lifer
Aug 27, 2002
10,043
2
0
Originally posted by: CrackRabbit
Originally posted by: ItTheCow
It might be the gas. It seems to always happen with my car during the winter season. I always seem to get a few less MPG. I believe they put in some sort additive to help prevent gas from freezing in your tank.
Click to expand...

Ding Ding Ding!!! We have a Winner!
Click to expand...
We don't do that in the south though.....It's possible your new compressor just takes a few more ponies than your old one, even with the clutch disengaged, your compressor could use anywhere from 2-12HP (depending on the compressor of course). I once had to replace a compressor in an old Ford Ranger I used to have, I went from ~20mpg to ~24mpg, simply because the aftermarket compressor I bought was more efficient, I've seen the difference swing both ways as I also had an old Crown Vic that went from ~25mpg to 18mpg by replacing the compressor.

Other possibilities, spark plugs, plug wires got moved and are now touching the chasis causing a slight drop in voltages, fuel injectors are dirty/fuel has water in it, tire pressure, thermostat, dirty air filter, dirty oil, dirty breather, o2 sensor, clogged/malfunctioning EGR valve....I'm sure I'm forgetting something....
 
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