# Altima MPG. Help.



## Teh00Alty (Jan 21, 2005)

Why is my altima only getting 19 mpg highway?


----------



## Xylob (Sep 12, 2005)

perhaps your foot is too heavy?
how are you computing your mileage?

the formula is simple: # of gallons used divided by miles driven = miles per gallon

I always fill my tank everytime I put gas in it, otherwise how in the hell do you know exactly how much gas you have used since the last time you put some in?

What kind of mileage do you get in town? I'm averaging about 21.7 miles per gallon in town.
I'll be going on a trip this weekend approximately 152 miles each way -- I certainly hope to be getting better than 19mpg!

When was the last time you had a tune-up or your regularly scheduled maintenance done? Flush & Fill the tranny? Oil change? clean your fuel system?
There are TONS of factors that could have a negative impact on your fuel economy, including underinflated tires!


----------



## Xylob (Sep 12, 2005)

okay, I just got back from my trip....
I got 31.62738 miles per gallon going up there.
and I got 27.20187 mpg coming back (head wind and a detour that ran me into a traffic jam...)
either you're not computing your mileage correctly, or there's something wrong with your car.
Again, there are more factors to list that could cause your poor mileage, or it could be a combination of many different things.


----------



## Darktide (Jul 29, 2004)

This is an average of over 1 year now. I've used Lucas FI cleaner on a regular basis, changed the fuel filter, did the spark plugs, wires, cap/rotor, and I get an average of 23mpg.. I drive a little bit of highway and a little bit of city each time (100 miles in town and 80 miles on a route that does 55 on average). I would LOVE to get 25+ but I haven't figured out how to increase it any more. As for you, check the following,

Fuel Filter
Spark Plugs
Cap/Rotor
Tire Pressure
Run Fuel Injector Cleaner

These are some of the more common problems. I wish you the best of luck


----------



## edge3333 (Sep 30, 2005)

*99 Altima mpg*



Teh00Alty said:


> Why is my altima only getting 19 mpg highway?


My girlfriend has kept meticulous track of her 99 Altima's mpg since she bought the car new. 26.2 mpg over 52,000 miles. On a 1000 mile highway trip a few year's ago (70 Mph average) we got over 30 mpg. She has only had normal scheduled maintenance performed. As of last week, the car is now mine!

Have you ever had the fuel injectors serviced?


----------



## Teh00Alty (Jan 21, 2005)

on a full tank i get about 230-260 miles to a tank.

whta about u guys


----------



## bobdole (Oct 10, 2005)

I average 350-400 per tank. Do you often take your alty to 4500+ rpms before you shift? You can try replacing your Engine Coolant Temp sensor. You wouldn't think that it would make a difference in your mpg, but if it is bad, it will cause you to run very rich, which will kill your mpg. On nissanclub.com, one cat went from ~19mpg to ~26mpg by replacing his, IIRC.


----------



## Johnjay7777 (Jun 11, 2005)

Teh00Alty said:


> on a full tank i get about 230-260 miles to a tank.
> 
> whta about u guys



230-260 that seems crazy.... i only get maybe 190 on a full tank... i had a tune up done about 6 months ago... plugs, wires, rotor, fuel system check and all that good stuff... i just got new tires about 3 months ago and invested in a fram air hog air filter... and continue to get about 14.8 MPG... all on a 98 with 108K on it... in the city... since im not to mechanical when it comes to cars how would replacing the fuel filter work... is it a PITA or could one do it on a saturday?


----------



## bobdole (Oct 10, 2005)

Hardest part about replacing your fuel filter is getting the hoses off (they're on there pretty good). It can be done in 15 minutes.


----------



## Johnjay7777 (Jun 11, 2005)

bobdole said:


> Hardest part about replacing your fuel filter is getting the hoses off (they're on there pretty good). It can be done in 15 minutes.



ok so getting the hose off is a pain but what about getting it back on? any special tools i need? do you think that this could make a difference, since i dont know if it has ever been changed?


----------



## bobdole (Oct 10, 2005)

It slips into place, so putting the hose back on is no trouble at all. When I did mine, I need a buddy to pull on the filter, and I held the hose with a wrench (for leverage) and pulled. It eventually came off. The hose slipped right into place. When you look at the filter, you will see why, because the filter is designed to keep the hose on. If your fuel filter hasn't been changed in a long time, and is dirty/clogged, then yes, changing it will help. I doubt it will solve your problems, but it should help. Same concept as replacing a dirty air filter.


----------



## gfriedman (Oct 12, 2005)

Maybe your tranny isn't shifting to high gear? How is the engine performing ? Do you feel any sluggishness? Maybe someone is siphoning off your gas? 

Geno


----------



## Teh00Alty (Jan 21, 2005)

no , no one is siphoning my gas, im sure of that. its not sluggy at all.
i drive like a jerk but it shouldnt have that much effect on it at all. 

SHould i replace the fuel filter, or even if i did would it make a big dif?


----------



## bobdole (Oct 10, 2005)

Teh00Alty said:


> i drive like a jerk


That's your problem right there. Next time you fill up, spend the entire tank driving like a grandma, i.e. accelerate slow, brake slow, top out at 65-70. Once the tank is empty, calculate your mileage and see what you get. View it as a MPG experiment. Post your results, and we'll go from there.


----------



## Johnjay7777 (Jun 11, 2005)

bobdole said:


> That's your problem right there. Next time you fill up, spend the entire tank driving like a grandma, i.e. accelerate slow, brake slow, top out at 65-70. Once the tank is empty, calculate your mileage and see what you get. View it as a MPG experiment. Post your results, and we'll go from there.



well what about me i dont drive like i jerk.... i barly get to 40 on the roads... and i still get 14 MPG....


----------



## gfriedman (Oct 12, 2005)

Johnjay7777 said:


> well what about me i dont drive like i jerk.... i barly get to 40 on the roads... and i still get 14 MPG....


Nah, the fuel filter is not your problem. Your problem is either your engine isn't tuned right, you have some blockage in your exhaust, your tranny isn't shifting right, or your brakes are dragging. 14 mpg is way low. Also check your mileage when you fill the tank at least 3 times and average it out so you get a more accurate picture. If you are driving and the car is performing well then it doesn't make any sense. When things are that much out of whack that you get 14 mpg you should definately feel a problem with the car's performance.


----------



## bobdole (Oct 10, 2005)

Johnjay7777 said:


> well what about me i dont drive like i jerk.... i barly get to 40 on the roads... and i still get 14 MPG....


Perform a full tune up (cap, rotor, plugs, plug wires, fuel filter, air filter, oil, oil filter, etc) and check/set your timing. After all this, report back with your mileage, and we'll go from there.


----------



## Johnjay7777 (Jun 11, 2005)

bobdole said:


> Perform a full tune up (cap, rotor, plugs, plug wires, fuel filter, air filter, oil, oil filter, etc) and check/set your timing. After all this, report back with your mileage, and we'll go from there.



I had a complete tune up about 3 months ago where all that crap was checked and replaced... before the tune up i was getting about 14.5 mpg and now i get around 14.9... i just had my rear breaks done about 2 weeks ago and the fronts within the last year... i know that it is not that the breaks are dragging... there is no noticable lack of preformence in my car it has the same kick if not more now that i put in a air hog air filter... as for the timing i was told by the moderator that i have a timing chain not a belt, and that this will last the life of the car... so what else is there to do... i hate having to put out 40 bucks to fill the take every 4 days...


----------



## gfriedman (Oct 12, 2005)

Johnjay7777 said:


> I had a complete tune up about 3 months ago where all that crap was checked and replaced... before the tune up i was getting about 14.5 mpg and now i get around 14.9... i just had my rear breaks done about 2 weeks ago and the fronts within the last year... i know that it is not that the breaks are dragging... there is no noticable lack of preformence in my car it has the same kick if not more now that i put in a air hog air filter... as for the timing i was told by the moderator that i have a timing chain not a belt, and that this will last the life of the car... so what else is there to do... i hate having to put out 40 bucks to fill the take every 4 days...



Check the tread on your tires. If the alignment is out of whack you will see abnormal wear patterns. Also, check to see that your transmission overdrive button is turned on - so that it shifts to overdrive.

Gene


----------



## bobdole (Oct 10, 2005)

Johnjay7777 said:


> I had a complete tune up about 3 months ago where all that crap was checked and replaced... before the tune up i was getting about 14.5 mpg and now i get around 14.9... i just had my rear breaks done about 2 weeks ago and the fronts within the last year... i know that it is not that the breaks are dragging... there is no noticable lack of preformence in my car it has the same kick if not more now that i put in a air hog air filter... as for the timing i was told by the moderator that i have a timing chain not a belt, and that this will last the life of the car... so what else is there to do... i hate having to put out 40 bucks to fill the take every 4 days...


Yes, you have a timing chain, but that does not mean your ignition timing is correct. You need a timing light to check your timing (clip it to the number 1 spark plug wire and aim the light at your crank pulley). Not sure if you said so or not, but are there any engine codes being thrown?


----------



## gfriedman (Oct 12, 2005)

bobdole said:


> Yes, you have a timing chain, but that does not mean your ignition timing is correct. You need a timing light to check your timing (clip it to the number 1 spark plug wire and aim the light at your crank pulley). Not sure if you said so or not, but are there any engine codes being thrown?


No he says the car runs great with no problems. I still think someone is siphoning his gas.


----------



## Johnjay7777 (Jun 11, 2005)

gfriedman said:


> No he says the car runs great with no problems. I still think someone is siphoning his gas.



Well i know that no one is siphoning gas... i am an anal fuel checker... i check the gauge at least 5 times on a 10 min ride... i also check it as i get out of the car... and since i leave my car in a locked house garage there is no way that it is being siphoned... as for the whole timing light thing i guess i didnt say it before... im a not so mechanical guy... i work full time and i go to school full time so i dont have the time to do it eiither... and having a timing light and a code reader is out of my league... and im on pace for a 13mpg tank... this week...it seems that as soon as it gets to about 3/8 of a tank the MPG just die... and the needle goes down... i thank you for the help but now you guys are going above and beyond my knowhow... if i had time i would bring it in to a mechanic ( my GF dad) but i cant live wo my car... and yes i know that if i get the problem fixed then i wouldnt have to work as much but i need to work... oh almost forgot the fact that i have new tires so the pressure and the tread is fine... 

any other ideas? maybe one that i could do in a few hours or should i bit the bullet and go bring it in>?

thanks again


----------



## Teh00Alty (Jan 21, 2005)

i drove like a grandma this week, and there is no difference at all. Still getting crappy mpg's.


----------



## gfriedman (Oct 12, 2005)

Johnjay7777 said:


> Well i know that no one is siphoning gas... i am an anal fuel checker... i check the gauge at least 5 times on a 10 min ride... i also check it as i get out of the car... and since i leave my car in a locked house garage there is no way that it is being siphoned... as for the whole timing light thing i guess i didnt say it before... im a not so mechanical guy... i work full time and i go to school full time so i dont have the time to do it eiither... and having a timing light and a code reader is out of my league... and im on pace for a 13mpg tank... this week...it seems that as soon as it gets to about 3/8 of a tank the MPG just die... and the needle goes down... i thank you for the help but now you guys are going above and beyond my knowhow... if i had time i would bring it in to a mechanic ( my GF dad) but i cant live wo my car... and yes i know that if i get the problem fixed then i wouldnt have to work as much but i need to work... oh almost forgot the fact that i have new tires so the pressure and the tread is fine...
> 
> any other ideas? maybe one that i could do in a few hours or should i bit the bullet and go bring it in>?
> 
> thanks again


Hmmmm....

I mean if you're sure that you're doing the calculations right then there is something wrong cause you should be getting twice that mpg. 

There are alot of things that will impact gas mileage - but most of them not that drastically. For instance underinflated tires will take maybe 1 or 2 mpg off. The only things I can think of that will cut the mpg so low would be :
a) a gas leak - but you would see or smell it
b) an exhaust blockage - but your car will feel sluggish - maybe someone stuck a potato in your tailpipe - that is an easy check.
c) transmission not shifting to high gear - you will hear the engine overrev at highway speed
d) brakes dragging - you could jack up the car and try to spin the wheels with your hands. They should turn without too much effort.
e) engine problem - but you would get the service engine light on your dash.


Those are the easy things you could check for. Other than that either live with the lousy mpg or take it to a pro who can check it out. You might want to see if the car is still under warranty and ask the dealer what is going on.

Hope that helps


----------



## Johnjay7777 (Jun 11, 2005)

gfriedman said:


> Hmmmm....
> 
> I mean if you're sure that you're doing the calculations right then there is something wrong cause you should be getting twice that mpg.
> 
> ...


I thank yopu for the effort but all those things are checked... just did a tire check this am bc it is gettign colder here on Long island and they were within 1-2 psi... everything else checked out ok...i guess ill ahve to live without my car for a day and take it in.... and bc i didnt say it in previous entrys i dont have a check engine light on...


----------



## edge3333 (Sep 30, 2005)

*Engine RPM*



Teh00Alty said:


> Why is my altima only getting 19 mpg highway?


Just a thought....... What is your engine RPM at 60 mph? Mine is just over 2000 rpm on my 99 Altima with A/T, and I get over 30 mpg on the highway. If your RPM is considerably different, it might mean a slipping transmission or no overdrive.


----------



## bobdole (Oct 10, 2005)

It is possible for you to run very rich (I'm talking about your air/fuel ratio here) without throwing any codes. BTW, what RPM is your idle at when you are sitting at a dead stop, but still in drive (I'm assuming you have an auto tranny here).

For a cheap thing to try, go and buy a new Engine Coolant Temp Sensor (see this thread for referrence: http://www.nissanclub.com/forums/showthread.php?p=2421187&mode=linear#post2421187), and have your g/f's dad put it in, as well as check/set your timing for you. You may not be that technical, but to do both of those should take your g/f's dad no more than an hour. And here's a hint, when buying sensors, it is best to stick to Nissan OEM parts.


----------



## Johnjay7777 (Jun 11, 2005)

bobdole said:


> It is possible for you to run very rich (I'm talking about your air/fuel ratio here) without throwing any codes. BTW, what RPM is your idle at when you are sitting at a dead stop, but still in drive (I'm assuming you have an auto tranny here).
> 
> For a cheap thing to try, go and buy a new Engine Coolant Temp Sensor (see this thread for referrence: http://www.nissanclub.com/forums/showthread.php?p=2421187&mode=linear#post2421187), and have your g/f's dad put it in, as well as check/set your timing for you. You may not be that technical, but to do both of those should take your g/f's dad no more than an hour. And here's a hint, when buying sensors, it is best to stick to Nissan OEM parts.



thanks for the info... i was just thinking about it and i realized that i might not have the correct spark plugs in... i read another thread on this topic before, i think it was talking about Pt plugs./// i know that i dont have those but what are the Nissan OEM plugs... and other than a dealership can i get them at an auto parts store?

let me know

oh about how much a plug would be nice to know too...


----------



## gfriedman (Oct 12, 2005)

Johnjay7777 said:


> thanks for the info... i was just thinking about it and i realized that i might not have the correct spark plugs in... i read another thread on this topic before, i think it was talking about Pt plugs./// i know that i dont have those but what are the Nissan OEM plugs... and other than a dealership can i get them at an auto parts store?
> 
> let me know
> 
> oh about how much a plug would be nice to know too...


Yeah, you can get the plugs you need at a parts store. The store can look up the exact plugs you need. Platinum are about $12 ea but last 3 times longer so it's a wash.

Gene


----------



## Darktide (Jul 29, 2004)

gfriedman said:


> Yeah, you can get the plugs you need at a parts store. The store can look up the exact plugs you need. Platinum are about $12 ea but last 3 times longer so it's a wash.
> 
> Gene



OEM Spark Plugs are NGK Laser Platinum... cost roughly $12/plug and they should only need to be replaced every 100,000 miles. I will also agree with a sluggish O2 sensor will not always throw a code, and the Coolant Temp Sensor is the other sensor to change. They both will change the amount of fuel being sent to your engine. Though I can tell you now that if you're getting 14mpg you have to have some serious performance issues. Anything to cause a 10mpg drop would be a drastic difference. *shrug* I wish you luck, and to think, i'm still upset about only getting 22mpg city/highway


----------



## edge3333 (Sep 30, 2005)

*Plugs*



Darktide said:


> OEM Spark Plugs are NGK Laser Platinum... cost roughly $12/plug and they should only need to be replaced every 100,000 miles. I will also agree with a sluggish O2 sensor will not always throw a code, and the Coolant Temp Sensor is the other sensor to change. They both will change the amount of fuel being sent to your engine. Though I can tell you now that if you're getting 14mpg you have to have some serious performance issues. Anything to cause a 10mpg drop would be a drastic difference. *shrug* I wish you luck, and to think, i'm still upset about only getting 22mpg city/highway


FYI: The platinum NKG plugs recommended in my 99 Altima manual are $6.99 at Checker Auto http://www.partsamerica.com/ProductDetail.aspx?mfrcode=NGK&mfrpartnumber=6371&parttype=960&ptset=A


----------



## bobdole (Oct 10, 2005)

For spark plugs, don't bother with the platinums. Buy a set of NGK coppers. They are cheap, and they work very well.


----------



## gfriedman (Oct 12, 2005)

I would pull the existing plugs and take a look at em. See if they are black which would indicate a rich mixture. Alternately, have someone drive behind you and see if there is any smoke coming out the exhaust which would indicate rich mixture. Do you do only stop and go in heavy traffic 14 mpg is way way low.


----------



## Johnjay7777 (Jun 11, 2005)

gfriedman said:


> I would pull the existing plugs and take a look at em. See if they are black which would indicate a rich mixture. Alternately, have someone drive behind you and see if there is any smoke coming out the exhaust which would indicate rich mixture. Do you do only stop and go in heavy traffic 14 mpg is way way low.



I do a bunch of stop and go driving since there is a stop light every 2 feet in my town and people dont know how to hit the gas... i am also a delivery person so i am constantly in and out of my car at the most 2 days a week... but i dont think that that would have much to do with it... i will pull the plugs when i have a chance and see...


----------



## gfriedman (Oct 12, 2005)

Johnjay7777 said:


> I do a bunch of stop and go driving since there is a stop light every 2 feet in my town and people dont know how to hit the gas... i am also a delivery person so i am constantly in and out of my car at the most 2 days a week... but i dont think that that would have much to do with it... i will pull the plugs when i have a chance and see...



That kinda explains it I think. You're going to get below the city estimate with that type of driving. I'll wager you probably let the car idle a whole lot too while delivering.


----------



## Johnjay7777 (Jun 11, 2005)

gfriedman said:


> That kinda explains it I think. You're going to get below the city estimate with that type of driving. I'll wager you probably let the car idle a whole lot too while delivering.


well lets see i deliver once a week now so it really cant kill my mpg that much. i just watched a my gas go from just under a half a tank to 1/4 in 25 miles... it just sucks... as for the idle while on a delivery it is a double negative if i idle i waste gas but if i restart i waste gas too...

AHHHH what to do... lol


----------



## Darktide (Jul 29, 2004)

edge3333 said:


> FYI: The platinum NKG plugs recommended in my 99 Altima manual are $6.99 at Checker Auto http://www.partsamerica.com/ProductDetail.aspx?mfrcode=NGK&mfrpartnumber=6371&parttype=960&ptset=A



FYI Haynes manuals are near worthless. On top of which I pulled NGK Laser Platinums from my car when I did the switch. *shrug* they only had 70k on them and I have a good feeling that they were original (and I worked at Advance Auto Parts, which I believe owns Checker, and on the parts catalogue Laser Platinums are OEM) Granted this is a 2000 not a 1999, and they did originally use standard copper plugs in them but why run a cheaper plug that doesn't last even half as long or run as well as the laser platinums? Price is a concern, but only $10-12 a plug and they can last 100k if you remember to change your fuel filter and don't run lean or rich.... *shrug* personal preference is all it runs down to.


----------

