# 99 Altima horrible MPG



## Corrail (Apr 24, 2007)

I just bought a 99 Altima from a local dealer for $5750. The car was in excellent condition as far as I could tell with 80K miles on it. This is my work vehicle for service calls and such and I noticed immediately that the cruise control did not work not only that but the gas was on empty so I had to fill it up. The dealership is going to cover the costs of fixing the cruise control but I drove the car 195 miles and had to fill up the tank. I was not happy about that at all. I brought the car to their mechanic and they diaged all the censors which are checking out fine. They did replace the fuel filter, do a fuel injection cleaning, and noticed that the car was burning fuel 5 degrees higher than it was supposed to be. After all that I have not noticed a change. Im at just over half a tank and im at 80 miles... Any ideas?


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## Brianz01Altima (Jan 17, 2007)

Some folks have claimed that replacing the coolant temp switch fixes the mpg problem. The part is really cheap and easy to replace, so it might be worth a try.


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## Kraut-n-Rice (Jan 10, 2007)

If you are going through that much fuel ,you will soon be damaging the catalytic converter . Such a rich mixture is dumping a lot of fuel there. The damage may already be done at the rate you are using gas.


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## Ryan's Altima (Aug 29, 2006)

O2 Sensors??? Even though you aren't getting a code, I know with mine the service light came on, it was the O2 sensors and then it went away on its own. I was told if the gas mileage got bad to change them. This was all around 90k


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## Corrail (Apr 24, 2007)

We replaced the fuel filter and after doing some math at the gas station my tank was on empty and after filling it up it showed that I had only pumped 11 gallons of gas into the tank. So even though the gauge says empty I still had around 4-5 gallons of gas in the tank. Is there a low fuel light to indicate that the tank is actually low on gas?


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## Ryan's Altima (Aug 29, 2006)

Corrail said:


> We replaced the fuel filter and after doing some math at the gas station my tank was on empty and after filling it up it showed that I had only pumped 11 gallons of gas into the tank. So even though the gauge says empty I still had around 4-5 gallons of gas in the tank. Is there a low fuel light to indicate that the tank is actually low on gas?




Yes there is, mine usually goes on at about an eighth of a tank left usually giving me about 3 gallons left in the tank.


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## LONDONDERRY (May 19, 2004)

I suggest you start off with the simple things first. Bring the car to a mechanic, AutoZone or a DIY (very easy) to see if there is a store code in the ECU, even if the check engine light is not on.

Afterwards I check out some of the common issues Altimas are prone for
Intake gasket leak, spray carb cleaner around intake maifold, if the idle quiets down you have a leak.
MAF, see if the wires are dirty.
Has the car had a complete tuneup?
Start there and let us know what you find out
Frank


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## Corrail (Apr 24, 2007)

LONDONDERRY said:


> I suggest you start off with the simple things first. Bring the car to a mechanic, AutoZone or a DIY (very easy) to see if there is a store code in the ECU, even if the check engine light is not on.
> 
> Afterwards I check out some of the common issues Altimas are prone for
> Intake gasket leak, spray carb cleaner around intake maifold, if the idle quiets down you have a leak.
> ...


I brought it to a mechanic and there was no code. Everything seems to be working fine as far as the censors go. I do smell a gas smell rarely on the road but don't know if its the car in front of me. I think the mechanic checked for leaks though.


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## Ryan's Altima (Aug 29, 2006)

How does the car run performance wise?


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## LONDONDERRY (May 19, 2004)

Did your car pass an emissions test? I look at the vapor canister, if it goes then that might explain the gas odor. Did the mechanic tes for a gasket leak? This is a very common issue with the Altimas, so make sure your mech looked at this.

Frank


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