# Poor Gas Mileage



## Tut (Dec 26, 2007)

I bought my daughter a 1991 Maxima with 120,000 miles, a real cream puff owned by an older couple (really!) I did all the regular maintenance, plugs, wires, air filter, belts, hoses, timing belt, etc. but the car gets HORRIBLE gas mileage.....under 14 mpg in town. What do I need to check? BTW, it runs smooth, no hesitation and starts good as well...and no gas leak that I can see or smell...

Thanks,

Tut


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## internetautomart (Mar 8, 2004)

check the driver and the driving distance.
I was getting 14s out of mine, because of how far I drove and when I drove.


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## Tut (Dec 26, 2007)

internetautomart said:


> check the driver and the driving distance.
> I was getting 14s out of mine, because of how far I drove and when I drove.


I have, and it still stinks! I ran it for a while in the garage last night and I am detecting a gas (not leak, but unburnt) smell. I'm guessing dirty injectors.


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## Tom 2000 (Jan 1, 2008)

Did you check/change the O2 sensor?

My car has 190,000 miles and I can still get at least 21 MPG in mostly city driving.


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## Tut (Dec 26, 2007)

I have not...but I will. Shouldn't the check engine light come on if it is defective? 

Thanks for your advice!


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## internetautomart (Mar 8, 2004)

Tut said:


> I have not...but I will. Shouldn't the check engine light come on if it is defective?
> 
> Thanks for your advice!


nope, it dam near never comes on.


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## Tut (Dec 26, 2007)

internetautomart said:


> nope, it dam near never comes on.


That figures....can I test it or do I just shell out $75 and assume it is toast and replace it?


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## Tom 2000 (Jan 1, 2008)

I'm not sure how to test an O2 sensor, but I agree that the Check Engine light never comes on. About 6 years ago, 2 of my fuel injectors went out. Car was obviously shaking and running really bad, but I still didn't get a check engine light.


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## Tut (Dec 26, 2007)

Tom 2000 said:


> I'm not sure how to test an O2 sensor, but I agree that the Check Engine light never comes on. About 6 years ago, 2 of my fuel injectors went out. Car was obviously shaking and running really bad, but I still didn't get a check engine light.


Thanks, I guess I'll be crawling under the darn thing.....


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## internetautomart (Mar 8, 2004)

Tut said:


> That figures....can I test it or do I just shell out $75 and assume it is toast and replace it?


yup, there is a test procedure in the FSM, using the ECU.
and I have them available for less than that


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## Tut (Dec 26, 2007)

internetautomart said:


> yup, there is a test procedure in the FSM, using the ECU.
> and I have them available for less than that


I don't have access to a factory service manual and I'm guessing the ECU is an electronic control or computer unit? As this car is new to me I am unfamiliar with it at the moment as far as the electronics are concerned. Is there a place to plug an OBD or OBD II reader? I am not going out to look now.....it is 20 degrees and blowing snow!! How much for your sensor?


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## internetautomart (Mar 8, 2004)

Tut said:


> I don't have access to a factory service manual and I'm guessing the ECU is an electronic control or computer unit? As this car is new to me I am unfamiliar with it at the moment as far as the electronics are concerned. Is there a place to plug an OBD or OBD II reader? I am not going out to look now.....it is 20 degrees and blowing snow!! How much for your sensor?


1. there is a link in the stickies with a pdf version of the FSM
2. there is a port to pull codes with a scanner, but no cheapo scanner can pull them.
3. about $60


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## Tut (Dec 26, 2007)

internetautomart said:


> 1. there is a link in the stickies with a pdf version of the FSM
> 2. there is a port to pull codes with a scanner, but no cheapo scanner can pull them.
> 3. about $60


Thanks for the info on the link...and I actually have access to brand spank-me-new advanced scanner which will do everything but the dishes.


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## internetautomart (Mar 8, 2004)

I doubt it will read the max. only high end (think $2k+) have the connectors for it.
Personally I use the MT2500 from snap-on which even used these days goes for $800


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## Tut (Dec 26, 2007)

I should be all set then. The motor pool garage where I work just bought one a couple of months ago and they paid over $3k for the unit.....should do the trick. Thanks for your advice.


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