kenshi

A gasoline antifreeze???

So I see it was spelled AND described wrong by kdaullary. I should have realized before I posted. For some reason I thought he was talking about a fuel component.

Thanks D & B for clearing that up. Never heard of HEET. I've used the generic DRY GAS at times. My bad.

JimmyH

iTrader: (2)

Different fuel formulations are part of the Clean Air Act. And if I am not mistaken it covers more than half the country. Also, if I am not mistaken, in most large markets, it is used on winter formulations as well now.

I would try changing your spark plugs. Even if they look good, there might be a problem with one of them. Get someone to get the part numbers from a service manual for you, there are three different types. Normal, hot and cold plugs. I would try different ones to see if it solves your problem.

Another thing, if you bought it used, the prior owner may have had mods, which affected the computer. After taking the mods off and selling it, it may take the computer time to readjust. ECU's do change the way fuel is delivered based on driving habits, I can affirm that.

Back when my commute was 30 miles a day, I used to drive like a normal person and get about 26-27 mpg. Now my commute is 80 miles, I drive like a maniac and get 20-23 mpg. Even now on long drives, driving 65-70 mph, the best I can get is 24 mpg. Because that is how my car is managing fuel.

And by the way, I have filled up with gas of every type there is (Mobil, Amoco, Citgo, Speedway, Marathon, Shell, etc etc) My fuel economy is the same from all of them, 20-22 mpg, depending on how fast I drove that tank.

Porkepik

I have a 2003 6 spd, I do about 18.5-20 mpg lately but the weather has been bad and cold up here in montreal +- minus 20 celsius(suppose about 0 fahrenheit) And my commute is about 30 miles per day mostly in traffic or in city. On highway I get about 22-24 mpg, never had the chance to see if better temps increase that because I bought the car last october. I redline it from time to time but this is exception and mostly drive according to speed limits with gentle take off.

BTW the mileage seems very bad when the car is cold and the trip is very short (2-5 miles). My other car is a subaru outback and the wife drives it for her travel to work (6 miles back and forth). She averages 13-14 MPG, When I was driving to work with this car on the same trip the max does everyday I was averaging 20-22mpg.

KRRZ350

iTrader: (29)

Yup, I wouldn't be suprised if he didn't think to check the transmission fluid level....... If it's down 1-1.5 quarts it will cause a barely noticable slip and your mileage will drop significantly. After driving for 10 minutes check on level ground with engine idling in park.

oxygen

seeing this thread was incredible to me. I often drive 160 miles back and forth to school and my MPG has varied anywhere from 19.6 (when racing another car for 30 miles at 100 mph) to 29.3 MPG. I now am consistantly getting 24.3 MPG with several trips up to 100-110 mph. And I thought 24.3 MPG was awful.. I will bite my tongue now. When I first bought the Maxima I was regularly getting 28 mpg back and forth to school but gas has gotten much ****tier thanks to ethanol, and I have developed a leadfoot since my Valentine One investment. If my car ever dips under 20 MPG consider it sold.

G/L on finding the problem, I don't know what else you could check if you have done all the recommendations that these guys have suggested. I think I'd just cut my losses and put it for sale - you're getting SUV MPG right now

dmpesso

Ok dudes heres the story, ive been getting 15 MPG ever since I bought the car about 6 months ago, ive tried everything, new air filter, fuel system cleaner, all that. Didnt work! So last weekend I changed my spark plugs, o BOY were my old spark plugs GONE! they were like all black and needed to be replaced my friend who installed them for me says. AND on top of that, the rear 3 were drenched in oil, due to an oil leak (I need a new valve cover supposely). Now, besides putting these new plugs in, i changed the PCV valve, flushed the tranny fluid AND power steering fluid. STILL I am getting about 15 MPG and its PISSING ME OFF!! WHAT ELSE can possibly be the problem? I mean I changed everything that would have made a big difference and I see no changes.. PS: My alignment is a little off becuz i recently modified my suspension about a month ago and never got an alignment so now my car pulls to the right. But I doubt this is the reason why my mileage didnt get better because even before the alignment issue my car has been having mileage problems, and being my old plugs were cooked, this should've helped the mileage, but it didnt! Any suggestions/ other problems it could possibly be?

Maxgig

iTrader: (5)

I don't know if this applies to the 5th Gen's like it does on the 4th, but have you looked at the O2 sensors and maybe your knock sensor?

Puppetmaster

iTrader: (48)

How are you measuring MPG?

What is your tire pressure?

What is your driving style?

dmpesso

Yea those are fine, my mechanic said they were, and they seem to be as they would have went off if something was wrong, i mean my service engine light came on the other day after i installed the plugs but then I erased the code and it never came back on so im guessing my o2 sensors are fine. what are some other reasons for bad mileage that are known? or is it the oil leak that is still giving me horrible mileage?

MaxBoost925

iTrader: (33)

I'm getting 15mpg driving normally

dmpesso

im measuring my miles per gallon by looking at how much gas I put in the tank, at this time it was about 12.5 gallons by how many miles i drive until the empty light comes on which is usually always about 180-200 the MOST. which comes out to about 15 or 16 MPG, my driving style is usually shifiting at 2 rpms and sometimes hitting 3 rpms once in a while when i need a little speed.. my tire pressure is fine i always keep that on point...

Puppetmaster

iTrader: (48)

Nevermind.... found your old thread and merged it because its the same topic again.

dmpesso

o, i was wondering wtf happened lol.. yea but this is completely differnet, ive changed alot of things and done percautions to see a change in mileage and nothing helped... is something like clogged or something? cuz i see people that hit 3-4 rmps CONSTANTLY DAILY and still get AT LEAST 20 mpg and i hardly hit 4 rpms i mostly hit 2 and sometimes 3 and i can even hit 20 MPG, its ridiculous.. what can it possibly be?

Puppetmaster

iTrader: (48)

That sounds like the wrong way round.

1. Fill tank to full
2. Reset trip meter
3. Drive as much as you want or until empty
4. Take note of trip mileage
5. Fill up tank to full
6. Take note of gallons filled
7. Calculate MPG
8. Repeat this several times and find average

It probably won't make up 4-5 MPG, but its more accurate.

dmpesso

trust me, thats not the issue, the way i calculate it is COMPLETELY accurate.. I go by how much gas is in my tank to how many miles I drive until it says empty, the problem is definitely not how im calculating it. its something else thats impossible to figure out.. one more thing, As i said before i flushed the tranny fluid... my friend who did it, put 1 quart less of what my car needs so I can check it later and bottom it out if it needs to be done. So maybe there is a little less tranny fluid in there then I should have, im gonna check today, but i doubt thats the issue.. could that be why?

NmexMAX

iTrader: (22)

I wonder what that engine code was?

Possible rich burn?

Get codes checked.

It is a sin for your AFR to be that rich.

dmpesso

the code was something about a throttle body position but my friend just plugged the green thing in a little harder, erased the code and it never came back... The plugs were pretty black and the rear ones had oil on them due to my oil leak cuz i need new valve covers(so i hear). how can i tell if im running rich?

NmexMAX

iTrader: (22)

wb O2 sensor

Did you perform the IAVL after you D/c'd the TB?

I would have someone check the codes, write them down, report back.

dmpesso

can you please speak in noob, i dont understand ANYTHING you just said...

NmexMAX

iTrader: (22)

All you need to do:

LA02MAX

iTrader: (3)

A wideband o2 sensor is a way to monitor your A/F ratio (the mixture of air and fuel for combustion). He advised to get one because not only are they good to have, but it's a very good (and accurate) way to troubleshoot something such as this.

IAVL = Idle air volume procedure as outlined in the stickies along with the ECU reset procedure and throttle body position relearn procedure...

To check the code, go to something like autozone and they do it for free or buy yourself a OBD II reader.

LA02MAX

iTrader: (3)

Alright, damnit. Stop posting a few seconds earlier than me on everything!

dmpesso

we did pull the codes when my service engline light came on, and that one code with the throttle body position or something like that came on, my friend opened the hood, there was this little green thing, he pushed it in a little more, and the code never came back.. there was no other codes tho so what else can it possibly be?

KRRZ350

iTrader: (29)

your tranny fluid is down a quart, refer back to my original post. You failed to mention the alignment thing. Fix those two things, along with the IAVL and TPS re-learn. If your still getting horrible mpg and you're positive the trans isn't slipping then have the fuel pressure checked. Your rear plugs were soaked in oil, it is your valve cover if the tops/outsides were soaked, not the tips/electrodes.

dmpesso

Well im gonna even it out tonight and check the level, buuuuut i am going to fix the alignment this weekend so hopefully my mileage will get better. How do i get my fuel pressure checked? and what do u mean "IAVL and TPS re-learn"?

NmexMAX

iTrader: (22)

Please READ the SITCKYS

maxguy07

wow, that's pretty bad, maybe you have dirty fuel intake system.

BMWHIGH1

The problem could be that where ever you fill up is slightly on a hill. so when you think your filling up your really not. Being as though the gas meter floats when going down or up hill in case you have noticed. so when you pull out of the gas station the meter is begining to adjust itself. AND SPEAKING FOR MYSELF I KNOW THAT WHEN I FILL UP I WATCH THE NEEDLE RISE THEN I PULL OFF AND NEVER LOOK UNTIL THE NEXT DAY. SO TRY IT.
I ALSO READ THAT OUR CARS ARE SUPPOSE TO GET 20CITY 26HIGHWAY AND 22 COMBINED AUTOMATIC. BEING AS THOUGH NEW TEST WERE DONE ITS BEEN RESET TO 17CITY 24HIGHWAY 20COMBINED. TO REALLY FIND OUT WHAT YOUR GETTING YOU CAN GO TO WWW.FUELECONOMY.GOV HOPE THIS HELPS

stocked out max

iTrader: (2)

Is it possible you could be leaking fuel?

NmexMAX

iTrader: (22)

I guess we'll know the answer to that when he returns from the Bahamas.

JohnWEngle

Here's a wild idea: Trade cars with someone for a tankful or 2 and see what kind of mileage they get. Then you can eliminate your driving style/pattern/habits.

OR

Drive the car for one complete tankful out and one tankful back freeway only - no stops/stoplights. (Road trip!!!)

Just shooting in the dark here: Another thought would be carbon build-up in the intake manifold and/or intake valves. This diagnosis usually requires disassembly.....

dmpesso

heres the story, i was getting a constant 16MPG(and TRUST ME I calculate it right so please dont flame me about calculating the MPG) so i changed my plugs and happened to notice the rear 3 were very wet, I thought it was oil and took it into Nissan of Bay Ridge(brooklyn) to get the valve covers replaced cuz I heard thats what causes this. They ended up giving me the car back saying they tested the valve covers and they were fine and the problem was the water pump leaking coolant. Is this possible? Now besides throwing in the new plugs, changing my air filter, PCV valve, doing a tranny flush, power steering flush. I dont know whats left to fix my mileage. I commute about 40 miles a day 90% highway/10% queens & brooklyn. To name any symptoms I can think of, is when shifiting onto second gear, I feel it shifiting a little as I feel the car bog bag a little, but when shifiting on other gears it feels perfectly fine.. Im so confused because Ive changed almost everything that are supposed to screw with your mileage and ive seen NO improvement, now it seems EVEN worse. I'll fill it up with $40 and get about 12.5 gallons of gas, and the EMPTY light will start flickering when the trip meter only hits about 180-185.. WTF? thats such ****ty miles per gallon for the driving that im doing and im not even heavy footed.. Im not getting an o2 sensor codes or MAF codes neither.. what can it be?

dmpesso

AND i did the alignment too...

dmpesso

The first time i EVER got a CEL was when that stupid throttle code came up, he plugged it back in, erased the code and it never came back. You said to read my compression, wouldnt a CEL come on if that was a problem? or do I just need to search for those codes? tell me exactly how please... and by slipping tranny do you mean this? sometimes when im driving at like 2 RPMS and im being light footed, if i touch the gas a little sometimes the rpms will go a little to like 2.3 or so and the car wont get anymore power, BUT if i press it a little harder thats when itll respond, is that a slipping tranny?

dmpesso

buuuuuuump

upstatemax

iTrader: (15)

Looks like I have to start going to confession again...


As for the MPG for the OP... You live in F*ing NYC... The traffic here is at least 5x worse than "normal" driving conditions.


You could replace/fix everything and only see a 1mpg improvement around here thanks to the TONS of lights, stop signs, traffic and constant on and off the gas pedal.

Just get used to it.

dmpesso

I WONT get used to it because thats not the problem, I know a BUNCH of people who live in ****ING NYC and get WAY better mileage than 15MPG especially considering im doing mostly HIGHWAY driving so it does have SOMETHING to do with why im not getting the MOST MPG out of my car, but not no 15MPG be real..

upstatemax

iTrader: (15)

Well then what is the problem?

Since you know so much why is there four pages of you not fixing the problem?

Bullard_07

ummm I'd say clean or buy a new air filter. May or may not work but its worth a try and maybe start running Royal Purple Oil instead of that AUTOZONE special penzoil your runnin' lol

dmpesso

eyo shut ur ****in mouth, no one is asking you ite smartass, i dont know **** thats why im here, but i DO KNOW living in NEW YORK is not the reason my ****in MPG are like this