Fuel mileage in the winter

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  #1  
Old 11-18-03, 05:22 PM
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Fuel mileage in the winter

I have always kepted track of my mileage on the 3 cars I have owned (I didn't start driving untill I was 25).
All 3 cars the gas mileage drops 10% to 20% in the winter time. I can understand some of this, but it just seems excessive.
My current car is a '89 Dodge Spirit 2.5L 4 cyl. with 90k. I'm compareing summer mileage with winter mileage of the same year, not what I was getting when I first got the car (38k 4 years old).
I drive the same all year round, don't take long trips, mostly to and from work (about 6 miles, city driving).
I have changed the plugs and cables, replaced the 'computer' (for another problem) kept the engine clean, change the air filter regularly, same with the oil.

I just recently changed the catalitic converter only because of it's age. I was told it wouldn't make any difference in performance which I disputed since I figured it can't be as effective as when it was new (I am concerned about air quality also).

I do realize my trips are short which accounts for most of the difference in mileage, but a 20% drop just seems excessive.

Any input would help. Thanks.
 
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  #2  
Old 11-18-03, 05:28 PM
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What your describing is perfectly normal. Gas engines require a much richer mixture in colder weather during warm up. Because you only drive 6 miles to work, the engine is spending most of it's life in the "warm up" stage. Your realizing a 20% drop in mileage yet your car is spending 80% of it's running time in enriched mode. Take some long trips in the winter and it will be a better average.
 
  #3  
Old 11-18-03, 05:32 PM
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Two things

The engine takes longer to reach operating temp, the mixture is enrichened while it is warming up. You will consume more fuel.

Other thing and I don't know if applies to your area is in the winter months they oxygenate the fuel which alone results in about a 10% decrease in mileage.

Larry
 
  #4  
Old 11-18-03, 09:47 PM
mike from nj
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perhaps the new cat can be slightly more restrictive, as i'm sure you didn't splurge for an original replacement from the dealer, many aftermarket ones are way smaller, and also slightly more restrictive. the increased backpressure will cause you to consume more gas.

an old cat on this vehicle will affect your gas mileage in one way, if it was starting to clog up(a partial restriction). if it was worn out, like 90% do, it will have no affect on gas mileage.

is ignition timing set to spec, is the oxygen sensor reading (switching) properly, are the tires inflated correctly, are the brakes slightly dragging, is the torque converter locking up properly, is the coolant sensor reading correctly, is the thermostat operating properly and of the correct temperature, too much a/c use (which includes the defroster too)?

all these variables will affect gas mileage
 

Last edited by mike from nj; 11-18-03 at 10:20 PM.
  #5  
Old 11-18-03, 10:18 PM
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I've had oxygenated (winter) gas lower my gas mileage by a minimum of 20% on one vehicle (some are more sensitive to it)
Winter short hops only, easily -10% on all
I've often wondered how much "greener" that vehicle is burning 20-35% more fuel (45% on short hops in the winter!)
 
  #6  
Old 11-19-03, 04:03 PM
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Originally posted by mike from nj
perhaps the new cat can be slightly more restrictive, as i'm sure you didn't splurge for an original replacement from the dealer,
is ignition timing set to spec, is the oxygen sensor reading (switching) properly, are the tires inflated correctly, are the brakes slightly dragging, is the torque converter locking up properly, is the coolant sensor reading correctly, is the thermostat operating properly and of the correct temperature, too much a/c use (which includes the defroster too)?
The gas mileage drop was noticed before the cat change also.
Haven't checked the timming and the O2 sensor was changed a few years ago, but hasn't been checked. Coolent sensor has been changed in the last 3 years. The therostat has been changed this year. No AC.
 
  #7  
Old 11-19-03, 04:33 PM
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You kind of answered your own question
All 3 cars the gas mileage drops 10% to 20% in the winter time.
Every car I have owned and worked on experiences the same.

For the reasons we gave you


Larry
 
  #8  
Old 11-19-03, 05:02 PM
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VideoBruce I'm proud to meet someone wth a concern for air quality and not someone attempting to bypass an emission control device.Thanks
 
  #9  
Old 11-20-03, 04:08 PM
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Originally posted by davo
VideoBruce I'm proud to meet someone wth a concern for air quality and not someone attempting to bypass an emission control device.Thanks
Thanks............I don't just think of myself. I also buy American when I can.
 
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