another bad gas mileage complaint any ideas

[tothemax]

i have had my 96 maxima 5 speed for about 3 or 4 months and i average about 15 miles per gallon no matter how i drive it i just had the O2 sensor replace and it helped a lil took it to 17 and i drove to louisville and back and i averaged about 22 with the cruise on 85 any ideas the air filter is fine?

[nj1sh]

check the knock sensor

[ZGadson]

Cold weather takes its toll on gas mileage. Optimum mileage is actually in the dead of summer. The more humid it is, the better your mileage. If you live in a climate where you get all 4 seasons (like I do in South Bend, Indiana) it gets really cold, then really hot - that can mean the difference of 5-15mpg less when its cold outside.

Wait till it warms up a little, then check all your sensors/sparkplugs & wires/fuel pump and filter/etc...

(My summer mpg average is in the upper 30s because I drive like an old fart. Right now its closer to 20mpg)

[Darktide]

a few more things. In areas where it gets below freezing, gas stations will put n additive in gas and that'll bring your MPG down quite a bit. Also, always check your tire pressure. That has a very big affect. Then I'd check your plugs and air filter. In fact, do the whole tune-up while you're at it. Change your fuel filter. And try driving closer to 70-75 and you'll see an increase there too. I get 23-24 mix in the winter on my 00 max. I'm hoping to see a jump to 26-28 in the summer. Good luckJay

[tothemax]

the knock sensor threw a code when my O2 sensor was bad but it went away when i replaced the O2 sensor how would i check it and how does it effect my mileage?

[Darktide]

if a knock sensor goes bad it normally won't throw a code by itself. It'll throw a code along with something else that's going wrong (hence, the 02 sensor). If it ever threw a code I'd just replace it anyway. It's not that bad of a job.Jay

[shortdogg1980]

is the knock sensor hard to get to on a 01 i30t? i'm averaging 17.2mpg i gotta do something to try to help it, i already done a full tune-up, with air filter and transmission service...........

[rxm6]

Cold weather takes its toll on gas mileage. Optimum mileage is actually in the dead of summer. The more humid it is, the better your mileage. If you live in a climate where you get all 4 seasons (like I do in South Bend, Indiana) it gets really cold, then really hot - that can mean the difference of 5-15mpg less when its cold outside.

Wait till it warms up a little, then check all your sensors/sparkplugs & wires/fuel pump and filter/etc...

(My summer mpg average is in the upper 30s because I drive like an old fart. Right now its closer to 20mpg)

Quick question...am I'm not trying to be smug in any way...but how does the cold weather take its tool on gas mpg? All these guys are trying desperately to shove cold air into their intake to make a better burn and thus more power. So wouldn't more power and better burn result in more economical use of your gas? Just a thought.

[Darktide]

because, everything else is cold not just the air. Not to mention that its normally across america that they put that additive in. Not to mention tire pressures will change when cold. There are a lot of factors that lead to a 2-4mpg drop (at least in NH).

2nd thought. to the OP. Your speed is seriously hurting your MPG. I notice a change when I have the cruise set to 70 versus 80. Sometimes it depends on the flow of traffic, I also drive on a lot of inclines due to the terrain around here.

Here are a few tips. Slow down, check your tire pressure. Those two alone could give you a lot of economy back, especially the tires, everyone seems to overlook them.

[MinisterofDOOM]

because, everything else is cold not just the air.

Exactly.

Also, horrible weather like snow does nothing good for milage either.

[Sentientbydesign]

Read my write-up!!!

zerothread/319146

[shannonk]

I only have an '87 Maxima, so I'm not sure what yours has in it for diagnostics. I know in mine I have the code box under the passenger seat with flashing red/green light sequences that correspond to different probs with the fuel system. Have you checked this out or had it checked out to see if it's something easy?

I don't know, maybe this is kinda obvious and you've already went this route - but just in case......

[nj1sh]

what should the tire pressure be to achieve optimal mpg