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altima 93 troubles with the gas mileage
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ioanmachiman
Novice
Feb 16, 2006, 5:52 PM
Post #1 of 10
(1989 views)
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altima 93 troubles with the gas mileage
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Hi
troubles with the gas mileage
i read somewhere that even you have replaced the oxygen sensor it may not work because the coolant sensor may be wrong and the ecm doesn't get into the close loop.
is this sensor connected to the temperature gauge?
if yes and the temperature gauge is working then it means the coolant sensor is working and the ecm gets in the close loop. (???)
what other sensors are important for getting into the close loop?
is the catalytic converter important for the gas mileage?
ty
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 16, 2006, 10:33 PM
Post #2 of 10
(1986 views)
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Re: altima 93 troubles with the gas mileage
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It's and old car now. Any codes showing up? T
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ioanmachiman
Novice
Feb 17, 2006, 7:49 AM
Post #3 of 10
(1981 views)
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Re: altima 93 troubles with the gas mileage
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hi
no codes shows up. Everything looks to work but
not in the design parameters (high gas mileage). Now i try to
check the sensors. I was wondering about the coolant sensor
or other sensors that are important for the close loop.
ty
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 17, 2006, 8:50 AM
Post #5 of 10
(1972 views)
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Re: altima 93 troubles with the gas mileage
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I take it you check mileage all the time which is good. With no codes as CarJunky said tire pressure is a biggie. Also if you are in cold weather the gas mileage will drop and there isn't much you can do about that.
AlsoII: Some gas pumps don't put as much gas in as others and a single gallon will throw off calculations. Good for you for keeping track as you could ward off troubles early which could save you some bucks. T
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ioanmachiman
Novice
Feb 17, 2006, 7:19 PM
Post #6 of 10
(1967 views)
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Re: altima 93 troubles with the gas mileage
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hi
there is a coolant sensor which sends temperature-info to ecm-computer and there is a coolant sender which sends temperature-info to the temperature gauge on the board. So, even if the gauge shows that the engine is worm the computer may have a different information. i have checked the sensor and the connectors were all grease. I had the feeling the connectors were oxidized and the previous owner put some grease on them. I have changed it and hope everything will be ok.
ty
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 18, 2006, 1:05 AM
Post #7 of 10
(1961 views)
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Re: altima 93 troubles with the gas mileage
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YES - the car knows how warm it is and adjusts for that. If if always thought it was cold it would run lousy and you'd get a check engine type light and a code.
What have you noticed in fuel use? I would expect mid 20s for that car with mixed driving.
I get about 5mpg with my plow truck but can make a few hundred bucks in NO time so it's mute. Just being funny and YES we care about your concerns and will do our best to help. T
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ioanmachiman
Novice
Feb 19, 2006, 12:10 AM
Post #8 of 10
(1957 views)
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Re: altima 93 troubles with the gas mileage
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Hi
I checked the old sensor and is working very well. I came to the conclusion that the real problem was the connector on the harness part. It was corroded and oxidized.
That would put an extra resistance, lets say few hundreds ohms, because the ecm computer doesn't see anything abnormal. So the overall resistance drops only to 800-1000 ohms and looks like an cold engine.
Then I took out the connector from the Mass Air Flow sensor. Guess what?
It was corroded. I cleaned it. I have cleaned the sensor too.
I think I will start checking all the connectors.
What can you do to improve the electrical connections? After cleaning a connector is that reliable? Can you put something so that green stuff doesn't get on the connection anymore?
ty very much Tom for your reply.
THERE IS NO SUCH THING AS OLD CARS! ONLY MECHANICS GET OLD!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 19, 2006, 12:56 AM
Post #9 of 10
(1956 views)
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Re: altima 93 troubles with the gas mileage
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Arggh: I've had great luck with a product we don't sell here TMK called Dynatex brake lube which is pure silicone grease. With connections clean and if the spade type just torque a little bit on the male end for a stronger connection but go easy. Then with a flux brush I grease the connection with the silicone and have NEVER had to re do one. They are NOT generally in the mail order biz but you can get this from .... JimABW120@CS.com .. It comes like tooth paste and with shipping will probably cost about $12 bucks for near a lifetime supply. The real bargain with pure silicone is that is as close to totally waterproof as any of the products get. T
PS: I have NO $ interest in this.
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ioanmachiman
Novice
Feb 26, 2006, 1:13 PM
Post #10 of 10
(1934 views)
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Re: altima 93 troubles with the gas mileage
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Car mileage raised from 14 to 18 mpg which is not bad for 150 hp, this season, and driving only in city.
i couldn't find the sealant but i got the ideea (silicon grease).
ty
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