Hey guys whats up? We had a Bad Gas Mileage thread in the I30 forum, and well the answers were good, but i figured i should try addressing this to the maxima owners.

Im interested in seeing your

-driving style
-loads in ur car
-avg mpg
-gas used

and other various tips

now this is all info u need to know about my daily routine driving habits and upgardes and replacements ive done.

now my problem is this. I just recently replace my Knock Sensor and my 2 forward o2 sensors, all hooked up and no codes in the ecu, checked and reset several times. Im running on 93 octane, and i introduced EXP4 Gas and oil additive lubricants. I get about 12mpg. Almost all of my driving is city miles, i dont need the highway too much. I go to school in the morning about 1 mile from my house, i go home at lunch, come back, drive home again and then go abbout 4 miles to work, go about a half mile from one building to the other and then back and then 4 miles back home. school is like 7:30 to 2:30 and then 3:00 to 5:00 im at work, this is a typical day for me. When i accelerate my rpms usually go up to about 2500-3000, basically im going about 30- 35 or up to 40 when the gear changes (its an automatic). I had a tune up about 7000 miles ago, and just had an oil change about 700 miles ago. I have a Paradox systems air intake and a stock exhaust system. I also have 2 12's in my trunk and the box all together weigh about 70 pounds, thats what i drag around all the time.

Now that you know my routine and all the little stuff, to me something still feels wrong. I just bought a new gas filter a 200zx one that is compatable that needs to be installed. Im not sure whatelse can be wrong seeing that i have no codes in the ecu. I know it can be a stuck valve sometimes thats it, or dirty injectors, but i used injector cleaner a few months ago.

What are all of your ideas on this?

 

You could try:
Clean TB
Spark plugs
Air filter
seafoam
fuel injectors cleaned

 

cleaned the tb when i did my intake, the filter is new i just put the cai on like 3 weeks ago, i can reclean the injectors, and new sparks isnt a bad idea

 

You can attribute a good portion of your poor fuel economy to the type of mileage you put on. You didn't state how long you warm your car up before you drive off. Regardless of that, you only drive 1 mile to school, go home, go back to school, go back home, go to work 4 miles, drive 1/2 mile and back, and drive 4 miles home. So on any given week day you are putting on about 13 miles and during most of this time your car would be warming up. This is the worst kind of driving you could subject your car to.

I would expect that your car would get more like 15 or 16 mpg under these conditions but I'm just guessing.

I recommend you don't drive your car to school. That 1 mile you are putting on 4 times a day is bad for your car. Over time you will get moisture in your oil, your exhaust system will rot etc. etc.

Walk to school. Why do you need to come home at lunch, to walk the dog? Take your lunch to school.

 

im a senior in HS, u dont stay in school, its a mile i aint walkin a mile, i have car hence the whole point of it, im going to AZ next year and my car comes with it wont be driven as much, i let the car warm up only in the morning for about 10 mins, all the other times no warm ups, plus its getting hot here anyway

 

yeah dude no offense but that was kinda gayy...WALK??? i dont think anybody in this forum would walk to school if they had a car

 

The best way to check gas mileage is NOT from tankful to tankful, but by filling it twice before doing the math. The more miles you put on your odometer, the more accurate will be your gas mileage calculation.

For example, fill up your tank in the morning without overfilling it -- when it clicks off, thagt is the signal to quit.

Let the gauge run down to between 1/4 and E, and then add 10 gallons to your tank. Again, let the gauge run down to between 1/4 and E, but this time, fill up the tank in the morning like you did initially.

Read the mileage on your odometer, and divide it by the number of gallons it took to fill the tank the 2nd time PLUS the 10 gallons you added in between.

Your MPH will be a lot more reliable.

 

Obviously I'm out of touch with high school kids in the US. I didn't realize it was beneath their dignity to be seen walking to school, even if they only live 1 mile away. No wonder obesity is such a prevalent problem in the US.

If new spark plugs don't solve the problem then I would suggest there is nothing wrong with the car.

No car will get half decent gas mileage doing the routine you subject your vehicle to and 10 minutes of warming the car up in the morning doesn't help your fuel economy.

 

yea u won't be caught dead walking around north jersey as a highschool kid. definitely change the sparks, check your tire pressure. 32f/29r or how i have mine 32 all around. I do a lot of driving around north jersey and i just changed my knock , but now have codes for o2 sensors. i still get 350 miles on a tank before i fill up [halfway down past the 1/4 mark]

if all else fails, lose weight, scrub rides off your friends, or kick your girl outta the car.

 

you dont need to warm up the car longer than 5 minutes.. and driving a mile to school will give you crappy gas milage

 

A 200zx gas filter? I think you got the wrong one unless you typed it wrong.

Maybe try getting a full tuneup.

 

yeah my bad 300 zx tt gas filter

 

grab a can of BG 44k and run it through your tank, works wonders.

 

Why not just fill up twice, COMPLETELY full, and divide the total miles driven in both by both the amounts of fill up's? I have to disagree tankful to tankful is definately a good way to measure, in fact I believe it's the best because 300-400 miles is a very accurate measure, the only time that you would need more is if you went from straight city driving to straight highway driving on different tanks, then you're mpg numbers may be skewed.



Anyways those short trips you take are whats killing you, if you warmed you're car up for 3-4 minutes before every trip, instead of only 10 minutes in the morning, I'd bet you get different results, and MAKE sure your tire pressure is between 32-35 up front and 32-35 in the rear.


EDIT: also what kind of rims/tires do you have on there? Tell me the tire size that's on there as well please.

 

dont need to wait to warm up your car, your wasteing most fuel on start up. your car needs a rich mixture on start up. until it gets into closed loop. the faster you get into closed loop, the more fuel economy you will get. so just wait 30 seconds when you start up your car, and then drive, but dont hammer it.

 

I disagree if you drive you're car when its completely cold it's going to burn more gas trying to warm things up. If I didnt warm my car up in the winter I got close to 18 mpg which is unheard of for me, i usually get 26-32 mpg, and 22-24 in the winter months.

 

Typically all you need to do is warm the car up for about 1 minute and drive slowly. Unfortunately, for the originator of this thread, if he did that the car would still be cold by the time he got to school.

I have to laugh. He warms the car up for 10 minutes and then drives to school. If he were to walk he'd be practically there by the time he drove there, would have some exercise to start the day, and wouldn't be griping about his crappy gas mileage.

 

No offense, but I'm with Rmurdoch, but then I live in canada too.

P.s. it is recommended by experts that to warm up - let engine idle for not more than 1 minute and then drive slowly till engine oil temp is normal. And thats for cold cold days, not when its 40 F or over 10C out

 

A compromise for the lazy one would be to walk to school in the morning and pick the car up at lunch time and drive it to school when its warmer. That would improve the fuel economy.

 

acutally if you wait to warm up your car, you are scraping away material from the cylinder walls. thus destroying your engine. the hotter your engine is the better effiecncy it will have. you'll be in open loop MUCH longer. and your computer will dump more fuel in the manifold. yeah and btw, short tripping your car is terrible. if you do that check your oil, i bet it reaks of fuel. and fuel doesnt lube at all. you'd have to change your oil more often.

 

yea u should drive ur car right after u start it

 

i only do it like that sumtimes, cause im waiyting for my sis to get done in the morning, haf the time it doesnt get warmed up, and i dont floor it b4 my car is warmed up anyways

so many various answers, oy

 

Regardless of startup time.

You driving the car for short distances is bad for the car. You will get bad gas mileage no matter what you do. Not much we can do about that.

 

That's basically what I told him some time back. Also, I haven't read anything that would suggest the present owner has ever put a quality mile on the car since he's owned it. Consequently, he doesn't have a clue what mileage the car is capable of delivering in its present mechanical state.

 

+1^^^^^^^^^^^^^^^

 

as it is murdoch, the car is 9 years ol, what the carhas been trhough b4 i got it i dont know, but from what i have seen in the car thus far, the car is better condition then when the damn thing rolled out of the factory.

now all of this is a typical day, that doesnt have anything else included onme just driving around or running any other errins, and its only been like this for a year, next year i go out west to ASU the car comes with, so the mileage will be diff

 

You obviously either don't understand me. It appears that the the vast majority of the driving you do is on this little circuit that you describe. Why don't you take the car on a decent drive sometime but fill it up before you leave and when you get back and report in.

I think you will be astounded to discover that the car is capable of half-decent mileage. Just don't flog it like a rented mule when you are conducting this experiment and save it for some time other than the busy Memorial Day weekend.

 

ill have to find a good palce to drive through, u also need ot remeber, i dont live next to an autobohn, i live in bergen new jersey, one of the most congested part of the states lol, i have asked several ppl what mileage they get on their cars, and they get like 400 to a tank, their tanks are smaller, and they do the same drives i do, granted they have different cars, but they are all 6 cylinders, and as powerful or more than mine, this is why i am curious to see wtf is up with my car, sumthing seems wrong to me thats all, do u understand me?

 

I do understand you and firmly believe there is next to nothing wrong with your car, other than perhaps requiring a new set of spark plugs. I routinely can get 500 miles out of a tank on straight highway driving and have 550 + on 2 or 3 occasions.