the past few fill ups on my titan have only lasted around 197 miles. i know the trucks dont get very good mileage but an average of 8.5 thats rediculous. i dont floor it or drive it hard i just putt around in it. i used premium gas this time and still no difference. its starting to tick me off.

Fuel economy is a hot topic with all the truck platforms. My Xterra has a 63 liter tank. I get around 400km to a fillup. But when I hit the highway that goes to 550km.

There could be any number of reasons. ( What is the current odometer reading on your Titan?)

A sensor(s) could be dirty. Air filter is dirty. A spark plug(s) could be fowled.Spark plug wire may have come loose.Cap and Rotor could need replacing.Fuel filter(s) may need replacing. I am not sure if there is more than one on the Titan but this does sometimes help.The computer may be able to tell you more if you can get the unit scanned.

It could have been a crappy batch of gas, or just old gas from the refinery is in the gas station's tanks. As fuel ages it loses some of its punch. That's why when you store a motorbike, sled or lawnmower the manufacturers recommend you either drain the fuel or add in a fuel stabilizer product before you store it. Old fuel can't propogate a clean burn like newly refined fuel can. You get rich smelling exhaust and that can cause Oxygen Sensor issues. (which the computer will pick up on).

I would need to read up on diagnosing O2 sensors before I could tell you how to check them yourself. It seems there is a manual check for just about every sensor on a Nissan. It just needs to be read about.

its got about 10,000 miles on it, im going to get gas today somewhere different to see if that helps. if it doesnt im gona call nissan and see whats up.

Nissan does has a claim that their latest series engines need a substantial break in period before you will realize optimal fuel economy. Don't be suprised if the dealer tells you the same story, because it's true.

My 2004 Quest got horrid milage until it hit 22,000 KM. (13,200 miles)it was around 12 -14 MPG for the 3.5L V6. Not great in my books.

With the odometer reading 36000 miles now it gets 20-21 city and as high is 32MPG highway.

ill give it some time, i used to get alot better gas mileage out of it average of 12. id get rid of it if i didnt love the truck so much.

There's something wrong with your truck then. You should be getting 14+ with combined driving and a reasonable right foot. I have friends getting 16+ on crappy Phoenix oxygenated gas with theirs in combined city driving.

Any idiot lights on?

As a reference, my Titan gets about 12-13 and I have a pretty heavy foot. 8.5 would appear way out of range. I'd keep an eye on the oil level in addition to the things Big-Bird already mentioned. Poor cylinder sealing can easily cause some serious gas mileage issues.

i hope its not that. i did a really good break in, changed the oil at 1200 miles never floored it. who know maybe it will get better.

I have more info about this issue:

A possible culprit to poor fuel economy can be the Mass Air-Flow Sensor.

Component Description

The mass air flow sensor is placed in the stream of intake air. Itmeasures the intake flow rate by measuring a part of the entireintake flow. It consists of a hot wire that is supplied with electriccurrent from the ECM. The temperature of the hot wire is controlledby the ECM a certain amount. The heat generated by the hot wireis reduced as the intake air flows around it. The more air, thegreater the heat loss.Therefore, the ECM must supply more electric current to maintainthe temperature of the hot wire as air flow increases. The ECMdetects the air flow by means of this current change.This is how the computer regulates fuel usage.

SOURCE: NISSAN XTERRA FACTORY MANUAL

If the wire is dirty, has a peice of fluff on it or it's oily the computer has to push more voltage through the wire to maintain a constant temp. This equates to higher resistance. Which can directly affect fuel economy. Basically by having the dirty MAFS the computer can be fooled into thinking you at highway speeds when you're in fact puttering around town. So you end up wasting fuel.

The wire resides inside the sensor body(look inside the red circle on my image)

The fix is simple.

Unplug the MAF Sensor.Remove the 2 screws used to hold the sensor in place.

(Do this part away from the engine and your paint job)Spray ONLY electrical contact cleaner at the sensor's wire and let it air dry.

Do not touch the wire with anything as it can be easily damaged. ( A new one is not cheap either!).

I just did mine today and it took 10 minutes. Easy fix you can do yourself!

If there has been a drastic drop in gas mileage and your still under warranty, I'd have the dealer take a look at it.