tee_edwards

I need help! Here's the deal:

I drive a 2001 Maxima SE with manual transmission. I've owned it since new, and it has 47,800 miles. It has had all scheduled maintenance, and is in excellent condition.

About 4 months ago, I got my second flat in short order on the stock Potenza RE92 tires (I have the optional 17" wheels, with 225/50-17 tires). The tires had always exhibited poor wet traction and a lot of noise, and since I was planning a cross-country drive I decided to replace them.

I bought Bridgestone Turanza LS-V tires, in the same size, based on positive reviews on tirerack.com. The Turanzas are a high-end "Grand Touring" tire, whereas the stock tires were a midrange "Sport" tire. The Turanzas have been a great improvement in terms of noise, ride, handling, and traction, but . . .

I used to get 23 MPG with mixed city/hwy driving. I now get 15-17 MPG.

I have taken the car in, and had an excellent local mechanic check it out. They checked the thermostat, O2 sensor and fuel delivery system, as well as plugging it into the diagnostic computer and checking the plugs. Everything checked out fine. The only oddity they noted was my Amsoil air filter - it is only 6 MO, but they recommended I try changing it out. I tried replacing it with a paper filter experimentally, but it hasn't done any good.

The car has not lost any performance that I can tell in recent months. As it happens I also had the car's 45,000 mile check performed since getting the tires, and it got a clean bill of health.

I maintain proper inflation, and experimentally tried higher-than-recommended inflation, with no benefit to mileage. My driving pattern hasn't changed, and in fact I got some of my worst mileage while driving nothing but highways cross-country.

I have consistently used premium fuel, as recommended by Nissan. Since my mileage went down, I have had one oil change, and Mobil 1 full syn was used. No help.

WHAT THE HELL IS GOING ON??? I can't come up with any explanation for the lost mileage. I can see how the Turanzas's softer sidewall might make SOME difference by adding to rolling resistance, but I've lost more than 1/4 of my mileage. I can't see any other explanation for this.

I have moved to Minnesota since getting the tires (obviously a potentially important detail), but the mileage dropoff started when I was still living in Washington State. I have spent several winters there before and never had a dropoff in mileage due to winter gas.

Any ideas or advice are more than appreciated. I don't want to be getting Excursion-type mileage when gas prices climb even higher this spring.

Cliff's Notes: 2001 Maxima lost 6+ MPG after changing tires. Car has been checked out to no avail. Seeking advice.

BlackBIRDVQ

iTrader: (15)

Have you had your MAF sensor repleaced lately ? If you didn't give that a shot. I just got 400 miles out of my tank of gas- 16 gallons to be exac. 80MPH highway driving, some city driving- 25% with some quick starts. I almost never fill up all the way due to loosing some performance with heavy tank of gas :P

Y2KSilvahSE

How long do you let it idle when you start it cold in the morning? Only reason I ask is cuz both places you are living in are very cold...and the Max's a real gas hog for the first 5 or 10 minutes when started...I notice my mileage goes to crap when the temps get down below 40 degrees....just a thought.

tee_edwards

I don't think the ambient temp is the main issue - I started to experience the problem when it was still fairly warm in WA.

I'll check the MAFS. Is that a DIY replacement?

tee_edwards

I see the MAFS is not a cheap part (my quick online search says $415). I'll have it checked, but is this really a part that could cause this kind of major dropoff in mileage?

Adi G. Wijaya

as far as i know, MAF sensor is not that expensive. It is less than $100 shipped. Ask Daveb.

nadeemp8

iTrader: (5)

yeah, talk to DaveB and he'll hook you up on the MAF.

tee_edwards

Wouldn't a faulty MAFS trigger the SES light or cause some problem with performance?

tee_edwards

UPDATE 3/11: Just came back from my mechanic. The alignment and brakes are fine. Still no idea what the hell's going on. He says he's willing to keep looking, but is reluctant to take my $80/hour, when the car runs flawlessly other than the mileage. Grrrrrr . . .

Lumbee1

Did the problem occur exactly when the tires were replaced? How long were you in Washington State and observing poor mileage before moving? Can't rule out MAF, but I don't think that would be the problem. You might consider taking it to another dealer for additional diagnostics.

Galo

One more thing to consider -and one suggestion:

To consider: the mandatory oxygenated fuel used in winter in some states wreaks havoc with fuel mileage somestimes. If you are using oxy fuels still at this time of year, wait a few weeks.

Suggestion: find a friend who is willing to swap wheels and tires and run the car for two weeks & see. It's the only sure-fire way of knowing, if everything else seems up to snuff....

Mang

I've only had the pleasure of owning my car for a couple of weeks, but I can attest to the poor mileage. It downs fuel the way I down beer on the weekends.

Is this a common problem that owners have noticed? I'm going to try to change my driving habits but I doubt that will make much of an impact. Oh well, I guess I got to get use to my thirsty-*** Max.

95BLKMAX

iTrader: (10)

MAFS will not always throw out a SES. In the case of the MAFS, like o2 sensors, there is such a thing as "a little bad", and the SES wont go off until the sensor is pretty much gone.

Have the voltage signal of the MAFS checked.

pharmer

I live in Minneapolis if you want to swap tires for a tank or so. I'd say have the MAF checked, then PM me if you're interested. My car is equipped with the optional 17's and 235/45 Continental ContiExtremeContacts - they are a UHP all-season tire.

With mixed city/freeway I usually get 300-320 miles per tank. All highway at ~80 mph I get 350-370 miles per tank. This is with a 2k1 SE/automatic.

Keep in mind that all gas in Minnesota is formulated with 10% ethanol. I totally support this for numerous reasons, but the ethanol makes the gas more sensitive to picking up moisture from the air or ground. Therefore, the stations need to have facilities that are in good shape to keep out the water vapor. My best advice is to go to trustworthy gas stations - i.e. Mobil, Shell, SA, or Holiday.

Also, I know that you've had the problem for a while, but parking your car outside can really affect mileage. I had a Jeep that I parked outside, and in the winter I noticed a 20 to 30% drop in mileage due to the cold. Internal combustion engines just aren't efficient when they're really cold.

khynex

iTrader: (1)

i got my max in august and was getting around 260-270 then along came winter which wasnt as bad cuz its miami but when its cold my max drives like a dream....u feel the difference and u can see the difference cuz i was only getting 220 a tank. right now im getting back up there im in the 250ish

2002 Maxima SE

iTrader: (3)

You can clean this part fairly easily:
http://www.my350z.com/forum/showthread.php?t=55677

Works for me.