I just got an automatic 2000 SE with 32,400 miles a few weeks ago, and I've been noticing that the gas milage is completely off the walls(not in a good way).

Last time I filled it with exactly 10 gallons, I reset the miles, and today the 10 gallons are nearly gone and I only got 98 miles...what? Im estimating that by the time all 10 gallons are gone I will get about 110 miles. So that makes like 11mpg, this is all city driving though; nevertheless I would expect it to be much better.

So now heres the hard part...what the hell can I do? The car is still under warranty so I would like to get this figured out while I can for free.

 

HAHA~! sounds like mine...i have a 2k2 and am averagin about 10 mpg...AND THATS keeping under 2400 AND putting it to nutral when cruising to a stop~!!!!! 2400 rpm~!!! its makig me REALLY mad....16 gallons got me 200 miles last tank...today im at 9 gallons w/ 101.6 miles....man...

well i was thinking, that my car ran rich, but that rich~???...

im thinking of getting an APEXi AFC
what do you guys think?
will it help?

 

You need to do this first....... empty the tank, fill it up, drive till it get empty, and fill it up again.

Then take that mileage and divide by the gallons to get a more accurate reading

Then come back and tell me what you get and we will work from there. Aint no way you getting 10mpg.

Dixit

 

yeah.. what BDJ said... if you still get the same results, try a diff gas station. You could have bad gas.

if that still yields 10mpg, you have a 2000 SE with 32,400 miles right? Coils or a bad O2 sensor is likely.

You should know that all newer V6 cars will get 14-16mpg in the first 8-15 mins of operation. it's an emissions thing. Once the exhaust heats up (cat, not the needle on the dash) then your mileage will improve. If you only have a 5 min commute, you will always get horrible mileage.

 

That is something people forget all the time.

I mean I even forgot that. I used to drive 17miles to work on the highway, and now only drive 2.5miles. I used to get 350+ per tank, now i dont get more than 265. But that is obviously because I dont even give the car a chance to warm up and go beyond the time of true mileage.

Dixit

 

i measure at the gas station....i see how much gas i use to fill up...to the first click...dont over fill....i just divid that # by the # of miles i've driven...

 

If you're after a trend rather than an indication of different driving conditions you really need to compute an average mpg over at least 3 fills. That's in order to minimize the uncertainty as to how full you really got it before it clicked off (keep in mind that whatever trips the pump off is subject to some variances).

Norm

 

what if i don't have a cat and on hte cali specs there isn't an O2 after the cat anyway, how would the car know when to adjust the settings if it has no way to measure what's going on in the cat.

 

in my 2k2 auto my gas light went on, and the trip said 25 miles til empty, but it only took 15.3 gallons. i get 260 miles per tank in the city. its pathetic.

 

BananaRama:

Did you check the air pressure in your tires? If they are low, by even 3 psi, it will affect your gas mileage significantly. Air pressure should be checked regularly, especially when the temperature changes as a result of seasons and the weather.

 

yup that's about what i get and i'm a 6-spd i should get slightly better mileage then that i mean wow. 260~ miles to like 15~gallons of gas. pothetic is right.

 

how much highway driving do you guys do? I average about 300 miles per tank and I always let the car warm up before I move.

Russ

 

I have a 2k w/ 60k and i do all city driving, i get about 275 to a tank running 93 octain fuel. I think I get horrible millage. I dunno what happened, but b4, i got alteast 300

 

dang. I'm going to stop complaining about my 2k1 se 5 spd gas milage. I get anywhere between 390 and 430 miles per tank, mixed driving. That tranlates to 24 to 27 mpg in my book.

 

No wonder I am getting bad gas mileage. My commutes average 7 minutes. What happens when you don't let your car warm up. I mean you drive faster than you should be driving to get to work on time, without letting the car warm up. But I don't mean flooring it. Do any emmssions related componets mess up after a while? How should you be driving within the first, I don't know, 5 minutes that it will take for your car to reach operating temperature?

 

There have been numerous threads on this.

Search on:

catalytic and converter and operating and temperature

or

mileage and temperature

etc.

 

i don't think you need to drive any differently (other than when it really is *cold* - per the dash needle). it's just that the cat works because it gets hot, that's what it's supposed to do, so while it's cool the engine is less efficient, and once that cat heats up the car runs cleaner and uses less fuel.

i get about 330 mi/tank on average, and that's a lot of in-city freeway driving, merging and slowing and passing morons and stuff, trips at least 10 miles or more. and fairly frequent power-shifting of my 2k auto... and busting out of parking lots... and racing triple8sol (and losing - so you know i'm flooring it! )... and it still seems to do ok, at 56k miles...

 

You guys are starting to make me appreciate my commute, I go 20 miles each way city/hwy mix and I usually get 23-24mpg. If I go on a longer trip it goes up, best tank so far was 27.8mpg. 2k2 6speed

 

MY 2K2 6spd get about 300 -325 miles on a full tank of 93 octane.

 

My 2k2 6spd gets around 21~25 Miles per gallon. Depending how aggresive I drive.

If I drive normally (shift at 2500RPM or 3000RPM) I get about 24miles/gallon. Its about right. Things that I do to save gas:

1.Keep Engine Tuned Up (Do all the schedual maintence)
2.Don't use your A/C unless you have to. (A/C makes engine work harder!)
3.Keep tire pressure to the recommanded pressure (Look in owners manual)
4.Avoid stop and go traffic, take the less traffic route.
5.Use synthetic oil. (I use Mobil 1 ONLY)
6.Empty your trunk! (Remove all excess weight!) Yes that includes your AWSOME SOUND SYSTEMS~~ lol
7.Cruse a constant speed and obey speed limit(There are exceptions ofcourse!)
8.Avoid increase in speed when claiming a hill (engine is already working hard~)
9.Hurry and put on a Aero Body kit to decrease drag ^o^


Would my gas improve if I run a setup of (Cattman Y-pipe -> Random Technology Cat -> Cattman Catback exhaust) to free up the flow? Assuming if I drive normally ofcourse.

 

I use to do around 340/full tank but now i'm down to 270.hmm, might have to go in for a fuel injection service.

 

It's not the cat's operation. It's that until the coolant temperature has reached some programmed value(s) there is a warm-up enrichment going on and that the engine is not running closed loop. And there is probably some additional enrichment going on courtesy of the IAT sensor as well.

Norm

 

My last Maxima, an 89 SE 5 spd, usually got around 21 mpg with mixed driving. I define mixed as a bit of "sporty" driving, and some grandpop driving. My new 03 SE Auto is slightly worse. I am getting around 18mpg. Highway is around 26 at 75mph. These are not calculations from the awesome trip computer though. They are as real a number as I can get. I do agree that you need to do your calculations with a few tanks of gas. It seems others are dissatisfied with 18mpg, but I don't mind it. I appreciate the extra power and the slight mileage difference.

RichK

 

could be a knock sensor problem

 

Go to your dealer and get the latest flash for your ECM. I think your fuel economy will go up by at least a few MPG. It is possible that this will be at the cost of some low end power. When was your car built?

 

what? wha wha?? flash.. increase gas mileage? what is this???
explain???

STOP COMPLAINING~!!! IM AVERAGEING 200-230 MILES A TANK~!!!!!!!! THATS DRIVING under 2500-3000....WHAT IS WRONG w/ my car~!!
dah..im going crazy???
im switching gas stations....
and yes my trunk is emtpy(w/ the exception of my backpack and sports bag) tire pressure at 40PSI(get rid of the "loose steering problem" i calculate on several tanks... ALL THAT GOOD STUFF....dah...would it be the whole fuel system or what? new injectors??
STUPID LYING NISSAN~!!!

 

HELL YEAH! I use to get 300, now i hardly hit 270 wtf is wrong?

 

Just drove from north of Atlanta to Ft. Lauderdale and back. ALL highway driving, averaging 76.4 MPH and I got 20-22 MPG...That translates to doing 90 and having to slowup for snowbirds and minivans doing 55 across 3 lanes of traffic and a LOT of 4th gear driving on I-95 between West Palm and Ft. Lauderdale. I have my Check Engine light on, probably an O2 sensor because of the Y-pipe but I am still satisfied with the mileage. I have to get that fixed and see what my mileage does. But heck....1400 miles and 67 gallons of liquid dinosaur burned....I am not going to complain, still cheaper then flying. I can say with some assurance, if I got my 67 year old father to drive the mileage would skyrocket

 

After getting my clutch replaced under the 6spd TSB, it felt like my car had lost lots of low end torque. I couldn't understand it, I was going crazy trying to figure it out. I brought it back to the dealer and they denied anything wrong. I suspected that the flywheel had been improperly mounted (it has to be lined up with the crankshaft by using a locating pin). The original dealer was a waste of time. I brought the car back to the place I had bought it and learned that the ECM had been flashed. My car was built late in 2001, I bought it in November 2001. It probably had an early release of the firmware.

Since the ECM flash, I have been averaging 22-26 mpg whereas before I had been averaging more like 18-22 mpg. To be honest, I'd rather have the low end back, but my mpg has gone up noticably.

If mpg is your top priority, bring the car to the dealer and find out if there is an ECM update. If so, I would bet that it will give you better mpg.

As a side note, the engine feels "smoother" throughout the power band now as well.

I am considering bringing my car back to try and get the early firmware re-flashed to the ECM. I miss the low end I used to have. The choice is yours . . .