# Fuel economy issue



## Leuthesius (Sep 7, 2006)

I have a 1995 Altima GXE and it has a 97 Transmission if that makes any lick of difference. It also has 2255xx miles on it.

In the past, my car has achieved fuel economy as high as 42mpg (and arguably higher) on longer trips. Lately however, even highway economy at those same speeds is only yielding me 25mpg if I'm *lucky*. Otherwise, I'm getting 18-23mpg and this is irritating the hell out of me.

My fuel gauge warked out about two months ago and I had to replace the fuel pump because the low fuel light died and I had no clue I was out of gas. 

With the fuel pump replacement, I replaced the fuel lines (the rubber hoses at least) and the fuel filter. I also replaced my spark plugs, my spark plug wires, and did a fluid exchange, as well as running some lucas injector cleaner through the first tank. 

My economy still sucks.

The question still remains: What could be causing this at this juncture?

1) Catalytic Converter
2) EGR Valve
3) Fuel Injectors
4) 02 Sensors (I am getting no computer errors about the 02 sensors)


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## Altima SSS (Oct 10, 2007)

Wow ... 42 mpg, that's hard to believe since these cars weren't rated anywhere close to that for even hiway mileage. Based on the info below, it looks like 30 mpg was the hiway rating for the 95 models. I'd suspect your calculation that yielded 42 mpg is off for some reason.

Nissan Altima Gas Mileage

My 94 model gets around 26 mpg in 70% hiway, 30% city driving, so I would imagine it would be about 30 mpg on pure hiway just as the rating shows.

I'd suspect the O2 sensor or the coolant temperature sensor. Also, the throttle position sensor could be off or bad which could cause it to run richer than it should.


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## Leuthesius (Sep 7, 2006)

That would depend on how fast your highway mileage is. That's running at about 65mph.


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## Altima SSS (Oct 10, 2007)

Leuthesius said:


> That would depend on how fast your highway mileage is. That's running at about 65mph.


Sorry, but I don't think there is any way you can possibly get 42 mpg no matter how you drive the car ... unless you're coating down a 50 mile hill with the tranny in neutral. These cars are rated at 30 mpg, so you might get 32 mpg at best, but no way 42 mpg. You need to rethink on how you are calculating your gas mileage.

My 94 gets a consistent 25 to 26 mpg with 70% hiway ... so I can see it getting 30 mpg with 100% hiway, but no way will it ever get 42 mpg.

Please explain how you've calculated to arrive at 42 mpg ... if that's the case then you could theoretically get 650 miles on a tank of gas.


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## Leuthesius (Sep 7, 2006)

The fuel tank holds 15.8 gallons (I know this because I've run it out of gas before). 
I have achieved 520 miles on less than 1 tank of fuel. 

It's not hard to do the math. When your odometer is set at 000 when you fill the tank, and you fill it up with approx 12.5 gallons when you stop, (and it won't hold anymore) you have reached 41.6 mpg. 

My car has done it. I'll note that the one time it did it I had literally just serviced the car fully. (02 sensors, fluid change, air filter, fuel filter, clean injectors, and spark plugs/wires)

I made the run from Northwest Arkansas to Wichita KS in about 2 hours, 40 minutes, with an average speed of just over 110mph running 93 octane fuel through the engine. The engine's innards were probably clean enough to eat off of. Upon my arrival, I did the tune up.

The return trip is when I got the incredible difference. I'll note that on the "to" trip, I managed to get all of 16-18mpg hwy, but eheh.... I'm sure you can understand why.


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## Altima SSS (Oct 10, 2007)

If you're actually getting 42 mpg then that's remarkable. What sized tires do you have on you car? You think your odometer is accurate?

Anyone else here really getting 42 mpg? If so, then why would mine only get 30 mpg if babied with 100% hiway driving?


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## LONDONDERRY (May 19, 2004)

Please forgive me but I doubt your car can get 42 mpg. Not even a small 1.8 liter engine in a Sentra gets that. If you post some real data to prove it you'll make a believer out of me, just saying it is not enough, prove it


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## focusedblur (Apr 17, 2008)

110 mph for 2 and a half hours? if I tried that I'd probably be slapped with a felony within the first half hour....no police down south?


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