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Discussion Starter · #1 ·
About 3000 miles ago i changed my O2 sensor because I was getting some bad gas mileage. After that it was good for a long time but now it is bad again could i have worn it out already?

Also what else could be efecting my gas milage b/c i only get in the mid 20's.
Could it be the cold weather? I also heard that letting a car warm up improves gas mileage it that true?
 

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Cold weather could decrease your gas mileage. I don't know about letting the car warm up helping, although it is a good practice anyways.

As for the O2 sensor, it shouldn't be bad yet unless it was defective.
 

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the_new_kid said:
About 3000 miles ago i changed my O2 sensor because I was getting some bad gas mileage. After that it was good for a long time but now it is bad again could i have worn it out already?

Also what else could be efecting my gas milage b/c i only get in the mid 20's.
Could it be the cold weather? I also heard that letting a car warm up improves gas mileage it that true?

Did you install the new sensor yourself? I have heard of O2 sensors failing quickly due to thread sealant getting into the sensor are instead of the threads.
 

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the_new_kid said:
Yes I did do it myself but what would the sealant do to wreck it?
If it gets onto the sensor portion itself, it fouls the surface and causes inaccurate readings or complete failure. Did you get any in the little louvers around the sensor?
 

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Discussion Starter · #6 ·
I don't know but i guess i will try to remove it.

I had a hard enough time finding something to put it on tight now i have to remove it.
 

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the_new_kid said:
I don't know but i guess i will try to remove it.

I had a hard enough time finding something to put it on tight now i have to remove it.
They make sockets especially adapted to O2 sensors. Try one of those. Autozone has a loaner program I think.
 

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If you did get some of the anti-seize grease on the tip, it seems that the 02 sensor would have been messed up from the beginning. There may be other causes of low gas mileage. Here are a few:
1. Cold weather, increased time engine is cold and running rich
2. Reformulated gas. Depends on were you live. It can reduce fuel economy.
3. Need a tune-up: Air Filter, Cap, Rotor, PCV, plugs (NGK recommended), and fuel filter. I have been doing these at about 30,000 miles. Air filter sometimes sooner. Check plug wires, replace if bad. Also, I am cleaning throttle body/throttle plate of carbon every 30,000 miles. If your throttle plate sticks a little open, it will contribute to poor fuel economy.
4. Thermostat sticking open.
5. Heavy foot. That is what gets me. :) It seems my Sentra runs best WOT, but it is not good for fuel economy.

This time of year, I get poor economy (Low to mid 20’s), when temperatures are below 40 degrees and it takes longer to warm up. That seems to be the main culprit. I installed a new thermostat a few weeks ago. Not much difference with fuel economy. It seems like this engine design takes a while to warm up in the winter. When spring comes, I will be able to get closer to 30 mpg without making any changes to my car.
 

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there's nothing wrong with your car dude, that mileage is right on for winter. warming up your car will not improve average MPG because your running the car for 5-10 minutes without moving...if you're not moving how can you get miles to go with the gallons? lol.

winter gasoline also gives poorer fuel economy. and the car being on "choke" longer due to cold reduces fuel economy. when it's on "choke" the car is running rich on purpose.

(our cars dont have a real choke, but they do something similar)

basically, winter is NO time to be guaging your gas mileage...too many variables. i get 24mpg in the summer, and 17mpg in the winter...yeah.
 

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You could always place a cardboard piece in front of the radiator. It's not going to hurt your engine in anyway. I had this problem... checked thermostat and cooling system and everything is good. Sometimes the engine just can't reach the normal operating temperature in extremely cold conditions. My thermostat opens the radiator circuit at 82 C , most of the ones you'll find for sale at autozone and other stores open up at 77 C.. THEY ARE KRAP!! . You may want to look at your air filter make sure its not restricted in any way, check your timing advance and tire pressure.
 

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Below 40 degrees I am putting two tops to "Sam's" clumping cat litter pails in front of the condenser. One on each side. They fit well, are easily removed, and that has helped warm-up time. Just started doing it this winter after a warm car cooled down at highway speed on an extremely cold day.
 

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Tavel said:
there's nothing wrong with your car dude, that mileage is right on for winter. warming up your car will not improve average MPG because your running the car for 5-10 minutes without moving...if you're not moving how can you get miles to go with the gallons? lol.
Actually, that is incorrect. Your car will run a leaner mixture when you first start rolling if you warm up your car first. This is not only because of the way the timing changes due to thermostat readings, but also because it takes time for the O2 sensors to warm up and start functioning properly (even heated ones take a while to warm up). Modern cars use very little fuel at idle too, so you're not wasting fuel in the long run by doing this.

I've tested all of this myself. I've actually had my mileage drop 10 mpg (that's not a typo) after not letting my car reach operating temperature before moving it.

BTW: I regularly get 35mpg on about 80% city driving out of my GA powered 200sx. On the rare occasions that I do mostly highway driving, I hit 39 or sometimes 40mpg. These values drop only 1 or 2 mpg during the winter, as I change my tire pressures whenever the outdoor temps change.
 

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Catman said:
Below 40 degrees I am putting two tops to "Sam's" clumping cat litter pails in front of the condenser. One on each side. They fit well, are easily removed, and that has helped warm-up time. Just started doing it this winter after a warm car cooled down at highway speed on an extremely cold day.
That's exactly what happened to me too... highway speed on a extremely cold day... my temp was normal and then started dropping out of nowhere. The lower temp is unacceptable for your lil GA16DE when you drive for almost an hour... you're wearing out the engine fast. The cat litter pails is original tho you should patent that. :)
 

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Discussion Starter · #14 ·
Wow i didn't know all this stuff now i do. I guess i will check at autozone and see if they have a loaner tool for o2 sensors.

I guess i do have a lead foot though. I start out good with the first 75 miles and then i see some one coming up on my tail fast and you can't help but downshift and floor it.

Also will it really help if my car gets up to temp in a normal amount of time to put something in front of the radiator? I have never seen my temp gauge move from that spot hot or cold out once i get my car up to temp.

Thanks again guys i will let you know what happens.
 
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