DCP

iTrader: (15)

I checked the codes, and didnt have any besides the one that says there are no codes. I was thinking the KS was my problem, but i guess not. Any ideas as to why my poor mileage? I drive roundtrip to work about 24 miles each day, at about 65 mph for 75% of the drive, 5 days a week and occasionally a 100 mile trip at about 55 mph, Below is my fuel mileage from gasbuddy.com,

Purchase
Date...........GallonsPurchased......TotalCost.... ...Odometer(miles)....MPG

2/12/2007.....14.550...................$34.18.......... 99,442................16.65
2/3/2007.......8.048....................$18.90........ ..99,205.................16.29
1/31/2007.....12.690...................$30.44.......... 99,046................19.76
1/24/2007......3.531...................$8.47........... .98,872................13.71
1/22/2007.....6.663....................$16.18.......... .98,812................16.99
1/20/2007.....15.182..................$36.42........... 98,680................19.81
1/14/2007.....11.069..................$27.00........... 98,399................18.51

I posted this with the columns nicely spaced, but for some reason it jumbled everything together, this was the easiest way to fix it.

buzpuck11

iTrader: (3)

Change fuel filter, air filter, plugs, just do routine maintenance things and your MPG should increase nicely.

9378max

iTrader: (1)

/agreed with buzpuck11. I have the same mpg that do you have, but its because of my driving style lol

shadyonedeath

iTrader: (10)

i've been getting 17 mpg also. But its wierd because it dropped significantly in the past 2 weeks.

Anything else i should check besides the tips listed above?

9378max

iTrader: (1)

well, o2 sensor killed my gas mileage. Also, any codes? other than that, what changed in the last two weeks lol

99BlackMaxMS

iTrader: (85)

You can expect to see a drop of about 3-4 mpg in the winter months, especially if you get a cold winter. I don't think thats your problem but thought I would mention...

ImmaSquashYou

iTrader: (7)

sometimes it also depends on the type of gas you are using, what stations are u using to fill up. I know that if i use BP all the time on ultimate, my gas mileage dies. If i use WAWA gas, it will die, getty also, and anything that isn't ultimate octance 93.

DCP

iTrader: (15)

we have been having a pretty cold winter, that certainly could be contributing, i use 93 octane, from usally Sunoco, Getgo, or Sheetz, I was thinkin since im so close to 100k i should do the tune up.. maybe clean the TB and run some seafoam through this thing. anything else i should do?

njmaxseltd

iTrader: (19)

Replace both front o2 sensors and your mileage should go back up. As o2's get old the signal they send back to the ECU may not be accurate. Still working, you woun't get any error codes, but they aren't accurately reading your exhaust gasses.

XAugusta MoonX

iTrader: (1)

Hahaha good times in Pittsburgh. Don't get gas from Sheetz.

99BlackMaxMS

iTrader: (85)

I run Mobil Regular 87 right now (b/c im still in high school) and I get 16 mpg when I drive how I want to (95% city). However, last week I brought the car from MA to CT and back and averaged 25.3 mpg doing about 75% highway 25% city. I think that if your car is used to higher octane gas, it may get worse mpg... but 25 mpg doing 75% highway and 25% city isnt too bad.

P.S. I just got the car a month ago, and because gas prices are on the rise again...I plan on filling the car with 87 octane on a regular basis, and every 3000 miles when I change the oil, run 93 octane w/ a fuel injector cleaner. Any thoughts?

shadyonedeath

iTrader: (10)

This something i can do myself? How much $ we looking at here?

andrei3333

if the o2's were bad and sent back wrong info to the ecu would that not throw a code ?

pmohr

iTrader: (26)

Not necessarily, if it were reporting lazily or plain sending the wrong data. If it's not sending any feedback signal, or the heater circuit dies, then it will throw a code.

TurTLe*

iTrader: (11)

no it won't, this case is sometimes refered to as lazy o2. the ECU normally just checks for a certain value at a time. But a lazy o2 has a delay or so in its reading. Altho it can be a correct reading but at the wrong time. The ECU won't detect that because the o2 data is still withing the specs but itsw just at the wrong time. say you floor it, the TPS reads that out dumps more fuel, the o2 should detect a rich mixture and should allow for more air to lean it out, but if there is a delay of 5 secs, every 5 secs your running rich. These are rare cases of lazy o2's i've seen on a couple of cars.

Since your in pitts, it could be due to maybe warming up your car every now and these. Pointless idle's at places like the store and stuff, because when your car is on and your wheels are not rolling you are getting ZERO mpg. Also you gotta factor in right now there is a winter blend of fuel at the pump to help keep from freezing. it normally takes it down 1-2 mpg. Well aleast on my cars for the past 2 years. I really don't think anything is really bad with your car. I get +1-2 more mpg then you but its not the same comparsion due to 2 diffrent people at diff locations.

If you have time and money, just slowly do a little tune up work here and there. like suggested plugs,filters, injector cleaners, o2's if you would like, you have a total of 2, 2 front heated and 1 rear o2. it is pretty simple to do actually, you need a specail socket, its like removing 1 bolt that is pretty much open access and disconnect 1 connector.

BumbleB80

Recently I changed my knock sensor and it appears that my mileage increased. Thus far I've got 185 miles on half a tank in NYC morning/evening rush hour traffic. If you wanna know it takes me about 1 and a half hour to travel 20 miles in the morning and about an hour back during the evenings. I used to get about 160-170 on half a tank in heavy traffic.

andrei3333

Well i replaced my downstream 02 about 3 weeks ago, the mileage is not significantly better, but slightly it is, very very slightly, it was throwing a code 0902 for rear 02 heater before.

I don't think its that significant to replace 02 sensors if they are not throwing any codes, if u can afford it go ahead, but its not necessary

esdsix

Try 93 high octane, change all your filters. If your due for tune-up go with only NGK plugs iridium or platinum. Oh yea, fuel filter a must, start there - replace it.
I cant remember the recommended mileage for replacement on those but its not astronomical. Some fuel system cleaner and or injector cleaner should help too.
Good luck!

DCP

iTrader: (15)

Im going to be doing a full tune up very soon, so i will keep you guys updated on how things are working out.

Thanks for all the responses.

DCP

iTrader: (15)

http://www.infiniti-parts.com/catalo...at=servicekits

Oil Filter, Engine Air Filter, Drivebelts, Radiator Cap, Upper and Lower Radiator Hoses, Wiperblade refills, and spark plugs

price is $135+ shipping,

The salesperson said the plugs are factory nissan plugs.

does this sound like a good deal? or am i better off just buying everything seperately?

Whats the best plugs to go with?

thanks

andrei3333

NGK platinums or NGK iridiums, the ladder last longer and is more expensive

spn350z

One thing not mentioned is tire pressure, it makes small difference but I would check this.

Any problems with tranny? Check to make sure auto tranny shifts. If manual clutch?

metal_god98SE

iTrader: (1)

Running 87 octane is not recommended at all....especially with the problems that 99's have exhibited. At least run 89 octane if price is a factor...only $0.10 more a gallon. The car's sensors will take a beating with 87 octane, and KS failure will most likely result. It seems like you are saving money, but the long-term effects of crap fuel will take its toll. There have been many fuel threads, and not attempting to flame ya, just giving good advice. If you cant afford to run the proper fuel in the Maxima, then drive a "HyunGAY"

2da mizzax

iTrader: (4)

^^^ nonsesne. 87 octane will kill a KS? I would love to hear the explanation for that one.

a clean system (valves etc) + a clean EGR system + proper plugs = making 87 ok since those are the things that cause preignition aka knocking. not saying 87 is better, but a clean 87 will not "beat up your sensors". especially a KS.

cpt

iTrader: (1)

I had a 95 that got 28 mpg, replaced it with a 96 that gets 22 mpg. Full tune up on both, no codes, everything the same. Go figure.

d00df00d

iTrader: (4)

What the heck do ladders have to do with spark plugs?

BTW, NGK iridiums are not more expensive than NGK platinums...

shadyonedeath

iTrader: (10)

I calculated my MPG, i still get 19mpg. I'll try fuel filter first.

Should i let jiffylube do it, or can i do it myself?

ewuzh

iTrader: (20)

I would think twice about going to JIPPY LUBE:

http://youtube.com/watch?v=LTJjqr0QbIk

matrix11229

I bought my car with a bad knock sensor and bad O2 sensors. At that time the car made 200 miles per tank(city only) .
So I changed the knock sensor and all 3 O2 sensors, did a tuneup and filters + tire pressure at 34psi and got almost no improvement.
I'm getting a minimum of 200miles per tank and maximum of 250 (diving in brooklyn stop and go traffic).

If it's 75% highway 25% city I get at least 17mpg.

matrix11229

I think the problem is in auto tranny wear and alignment

ImmaSquashYou

iTrader: (7)

wow...thats awesome.........i guess its true, how are you suppose to know???

andrei3333

the ladder is an english language expressions meaning the second

d00df00d

iTrader: (4)

L......A......T......T......E......R

http://dictionary.reference.com/browse/latter










(BTW, you said "expressions" plural.)

andrei3333

thats fine, thanx

what r u an english buff ? i thought u were here for the maximas, not as a teachers assistant!

d00df00d

iTrader: (4)

If spelling words correctly makes me an English buff, then yes, that's exactly what I am.

TunerMaxima3000

iTrader: (4)

sorry man just wanna let you know thats not true. a clean system has little to do with predotonation and knocking, 87 octane and 89+ octane have different characteristics, the maxima at its compression ratio and setup is made for 89 OCTANE!!!!, Using 87 will not save fuel, your mileage will go down, and the chance of pinging or knocking due to improper detonation will go up!!!!!!!

just my opinion man the car is made to run 89, it sucks, i'm poor too, but you NEED to run 89.
P.S.> running a higher octane in a stock maxima wont do you much good either for you guys runnin 93, waste of money and can cause the same problems, even more so than running 87.(obiously unless you're boosted,etc.)

2da mizzax

iTrader: (4)

a clean system has nothing to do with predetonation and incomplete combustion? wow.

glad I work on my own car.

Do you know the purpose of an EGR? you do realize that a combustion chamber that is too hot will cause predetonation right? you do realize that the EGR system cools the combustion chamber right? you do realize a clogged EGR system will result in a higher temperature combustion chamber right?

TunerMaxima3000

iTrader: (4)

I realize all this, I was simply trying to say, on topic of fuel type, the distinguishing differences.
Not to say that all things you mentioned dont effect the detonation, simply that using 87 will cause large issues, cleaning EGR, etc. is part of maintenence, you can do all that and if you still only run 87 in an engine DESIGNED for 89, you are going to have problems.
thats all Im saying man, not trying to bash what you said.

matrix11229

Will a partially clogged EGR system reduce my gas mileage in the city (no highway) ? My small egr pipe is partially clogged near IACV valve but I have no codes.

d00df00d

iTrader: (4)

Um. If there was any octane the 4th gen Maxima was "designed" for, wouldn't it be 91 as stated in the owner's manual?