Bad gas mileage

[farmallbn]

I have a 2006 Nissan Pathfinder 4x4 and lately have gotten terrible fuel mileage. It is my wifes car. When we first bought the car it had less than 30,000 miles. It now has 50,000 on it. It started out getting 18 to 20 mpg. Now all we are getting is 15 to 16 1/2 mpgs. I use premium fuel and my wife has not changed her driving at all. I know it is winter now, and she does let it run about 5 minutes before she gets in it, but I cannot believe it would drop that much. I have no check engine light coming on and it seems to run great. The only thing I notice might be a little different, is in the morning when she starts it up, it does rev a little high for a little while and then goes rate down. I think that is normal. Not sure what to do. Can anyone help. I have read up on the ethenal, but I still don't think it would make that big of a difference. Thanks

[Encryptshun]

Is your loop mostly highway or mostly city?

My Xterra has the same drivetrain as your Pathfinder and what you're getting is pretty much what I get.

[farmallbn]

It is country driving for about 5 miles than 20 miles on highway one way. I am wondering why it changed though. It kind of changed slowly. going down

[Bubba1]

I have a 2006 Nissan Pathfinder 4x4 and lately have gotten terrible fuel mileage. It is my wifes car. When we first bought the car it had less than 30,000 miles. It now has 50,000 on it. It started out getting 18 to 20 mpg. Now all we are getting is 15 to 16 1/2 mpgs. I use premium fuel and my wife has not changed her driving at all. I know it is winter now, and she does let it run about 5 minutes before she gets in it, but I cannot believe it would drop that much. I have no check engine light coming on and it seems to run great. The only thing I notice might be a little different, is in the morning when she starts it up, it does rev a little high for a little while and then goes rate down. I think that is normal. Not sure what to do. Can anyone help. I have read up on the ethenal, but I still don't think it would make that big of a difference. Thanks

I'm also curious about the type of driving. Is it mostly highway, or local stop/go? That could make a big difference. 15-16.5 on a boxy SUV (with a roof rack?) is not all that bad. There are some easy things to check out, including checking for low tire air pressures, or a dirty air filter, dirty fuel filter, perhaps old spark plugs. If the area around the tailpipe has soot, perhaps you're running a tad rich.
Double check for unnecessary stuff in the back. Lightening just 100 lbs can improve 1mpg. Check how your tires are wearing. If they're not wearing evenly, you might have found your culprit.
Oh, warming the car up 5 minutes wastes gas. 30 seconds should be plenty on a cold day.

Good luck.

[PEZi]

how long have to had the car? did it do this last winter as well? gas stations use different additives in the winter and that can cause a drop in fuel economy, but if it has never done it before then i can't really say

[PEZi]

Oh, warming the car up 5 minutes wastes gas. 30 seconds should be plenty on a cold day.

Good luck.

^this... on newer fuel injected cars with modern oil systems... 30s to 1 min is PLENTY

to warm it up the rest of the way, you simply need to baby it (no high revving/hard accelerating) until it warms fully.

[farmallbn]

The tires are getting down to about 4/32. We are using 91 fuel all the time. I use 5w30 full synthetic every 4500 miles. I am not sure when I should change the spark plugs. It only has about 50,000 miles.I also thought about o2 sensor, but I have no codes yet. It is hard to believe the plugs are bad already. Thanks guys for helping me out. Any thing else you can think of that might be.

[PEZi]

The tires are getting down to about 4/32. We are using 91 fuel all the time. I use 5w30 full synthetic every 4500 miles. I am not sure when I should change the spark plugs. It only has about 50,000 miles.I also thought about o2 sensor, but I have no codes yet. It is hard to believe the plugs are bad already. Thanks guys for helping me out. Any thing else you can think of that might be.

well... check the last responses i left for you... other than that, no, not at this time

plugs from the factory are supposed to be good for 100k

[farmallbn]

Thanks, it is just friving my wife crazy. How bout some of the things from nissan. like different type of air intake. Would that be worth the buck. I know it is a suv, and they never get good fuel mileage, but we are just trying to get it back to normal.

[Kompresshun]

Thanks, it is just friving my wife crazy. How bout some of the things from nissan. like different type of air intake. Would that be worth the buck. I know it is a suv, and they never get good fuel mileage, but we are just trying to get it back to normal.

I wouldn't waste your money on an intake, maybe a drop-in K&N filter and/or maybe an exhaust upgrade. I would think cold weather would be the culprit though, I don't get as good of fuel mileage either in the winter.

[Encryptshun]

Did she recently starting driving it in 4x instead of 2x? That would sure as hell kill the mileage as well.

Oh, and regarding the 'warm up' comments, there's warming the vehicle up and then there's warming the vehicle up. In the winter, I let mine run in the morning until the heater starts blowing warm air. I park outside and I don't like ridin' chilly.

[Dattebayo]

Winter gas is oxygenated and makes you lose a point or two just from using it.

I would suggest maybe one or more of your brakes needs looking at or something in the driveline is causing your bad mileage.

[nissangirl74]

Thanks, it is just friving my wife crazy. How bout some of the things from nissan. like different type of air intake. Would that be worth the buck. I know it is a suv, and they never get good fuel mileage, but we are just trying to get it back to normal.

We replaced the intake in my truck. Didn't make any difference in my mileage, just better engine performance. My truck and your Pathy have the same engine. I get 18mpg almost religiously, unless we are hauling a car...up a hill....doing 80. If your wife is driving in 4x4, it will reduce the mileage. As far as warming the car up for 5 minutes in the morning...a motor that is running but is not in motion, gets 0 mpg. Just something to think about. Good luck! keep us posted.

[Dittoz7]

Bust out the MAF and Throttle cleaner.

[Dattebayo]

Bust out the MAF and Throttle cleaner.

That doesn't affect gas mileage.

[Dittoz7]

It did mine. But mine did have 195k miles...

[Dattebayo]

It's a different style MAF, dude.

[ricebike]

still a good thing to clean out the throttle body butterfly valve...

but agree that it's the combo of longer warm up times, and winter blend gasoline with that "up to 10%" darn ethanol diluting the pure gas mixture to boot

happens to my minivan and other vehicles