JMAXIMA

hey... i believe i've asked this before, but i thought i'd try to get some new responses. my gas mileage is still not so hot and i've done everything i can think of to improve it. i've changed the fuel filter... cleaned my TB... cleaned my air filter... put my stock air intake back on... checked my tire pressure... checked my brakes... checked for codes (0505)... changed my tranny oil (not synthetic though)... and i run nothing but 93 octane... and i use 5w-30 mobil synthetic. what else can i do? oh, i'm getting about 19-21 mpg city and 24-25 hwy... compared to a year or so ago @ 23-24 city and 30-32 hwy. thanks.

Sin

Don't forget, a lot of it has to do with how you drive.

JMAXIMA

my driving habits are fairly regular... i take it pretty easy except for the occational stomp on the gas to get the blood flowing. i've actually slowed down alot in the last year b/c i can't afford any major car repairs like i had on my Supra. is it possible i've done some internal damage from taking it to the strip a few times?

Sin

Check your knock sensor.

JMAXIMA

i'm not pulling any codes... is it worth pulling the KS and 02's to clean them and test voltage? i tried the o2's a few weeks ago, but i couldn't get them out. any suggestions? oh, and i changed my plugs (ngk plat.) about 6 thousand miles ago.

KMax2988

Another idea would be to check your evap valve and canister. Even though your not pulling any codes on it, it may be going bad or have a leak. I noticed my gas mileage had decreased about a year ago, and just recently (3 months ago), a code came through as an evap small leak. After I replaced both the valve and the canister, I noticed my gas mileage increased substantially. Figured maybe this might help.

JMAXIMA

KMAX... doesn't that have to do with the A/C system? if not, what does the evap valve and canister do? thnx.

KMax2988

Well, the evap valve and canister are located behind your left rear wheel. What this does, essentially, is turn gas vapors in your gas tank back into liquid form before they escape into the atmosphere. You see, inside the canister is charcol and when this charcol comes in contact with gasoline vapors, it causes these vapor to condense back into a liquid state in turn letting less gas escape from your tank.

JMAXIMA

ah, cool, thanks man... i'll have to look in to it. oh, how much was the total of that repair?? and how did you know it was in need of repair?

KMax2988

Since I work at a Nissan Dealer, I was able to get a few techs help me decide whether this was the problem. First off, the engine light came on in which a Evap-Small Leak code came through on the computer. Now, the techs were puzzled by this because it could mean one of two things; either the gas caps leaking, or the evap valve is leaking. We checked the cap, it was fine. Next, we checked the valve. The bolts were rusted in and when I went to take them out, they spun meaning they stripped. When that happened, it meant that the valve was definately leaking where it seals to the canister. So I looked it up on the computer at work and found out also that in 98 and up, they upgraded to a better canister and valve. I put this one in my car (mines a 96) cause the valve has a better seal on it. The part numbers are: 14935-54U04(valve) and 14950-56U18(canister). The parts list for $32.25(valve) and $44.25(canister), and prices do vary from dealership to dealership. The cost for labor I don't know cause I did the repair myself. Post back if you have anymore questions.

eibachmax

correct me if i am wrong, but when you open your gas gap, you should hear pressure being released? thats a sign that the evap is working correctly?

genepool

I would really like to know if the tank should make a hissing noise when taking off the gas cap. I don't think my car hisses

KMax2988

Your gas cap should hiss when unscrewing it. That will mean that it's holding pressure correctly. As for that meaning the evap is working correctly, it doesn't.

theblue

don't forget the most commonly missed thing when it comes to MPG that is changing... THE WEATHER - how is the weather this year compared to last year? fuel consumption will change.

95seMax

iTrader: (11)

[QUOTE]Originally posted by JMAXIMA
[B]hey... i believe i've asked this before, but i thought i'd try to get some new responses. my gas mileage is still not so hot and i've done everything i can think of to improve it. i've changed the fuel filter... cleaned my TB... cleaned my air filter... put my stock air intake back on...

why did you put your stock air filter back on , I'm assuming you ment the flat one thats in the stock air box, does the stock air filter save more gas than an aftermarket intake , which is better for the car , stock airfilter, or aftermarket intake??did you notice more gas being burned with the intake than the stock air filter??

thanks all

JMAXIMA

why did you put your stock air filter back on , I'm assuming you ment the flat one thats in the stock air box, does the stock air filter save more gas than an aftermarket intake , which is better for the car , stock airfilter, or aftermarket intake??did you notice more gas being burned with the intake than the stock air filter??

thanks all [/B][/Q

i did notice a slight increase in mileage when i put it on a couple of weeks ago. but i'm only on my second tank since it was back in... so i can't say for sure. i got 21 mpg instead of the normal 19 mpg. but this tank isn't looking nearly as good. probably like 17 mpg. but when i first changed my intake back, it was like 70 deg. for a few days... and on this tank its been in the upper 90's. i don't know what to do about this. i'd say it was the weather, but even last winter i was only getting 20mpg.

chris j vurnis

Maybe my evaporator canister is bad.
I just got in my car after about a month of sitting in the garage.
After a few minutes of driving, the fuel guage went down almost a quarter tank.

So if its evaporating, I'd say its about a gallon a week.

JMAXIMA

sorry to revive an old thread, but i did a little experiment this weekend. sunday morning i took a trip to the beach to take my parents boat out... its about a 130 mile drive... i did about 90-95 the whole way (no one on the road @ 7am)... i got about 22mpg. that night on the way home, i drove the speed limit.. 70mph the whole way home... i got 28 mpg. that is much better than i have typically got in the past year or so, but i have got the same mileage going 80 or so driving (uphill) to the mountains. so a question to all of those getting 27+ mpg hwy, how fast are you driving when you get this mileage? 65-75-85mph?? thanks. (please no reaming for going so fast )