Low Gaw Milage

I am thinking your oxygen sensors has failed forcing the computer to run the engine on a rich fuel mixture.

Wait--- I had a problem with my knock sensors and the EGR valve....got the EGR valve cleaned and my engine light was gone...and never bothered to pay attention to the knock sensor as I guess this doesnt glow the engine light???

Kyb> >I have a 97 SE Maxima. Runs great has about 190K miles on it. There is

The knock sensor code sometimes pops up with other codes. Check it again and see if its still there. A bad knock sensor will lower the mileage to what you would get running regular gas instead of premium. 18 is pretty low unless you are doing all stop and go city driving. If this is highway miles, then you have more problems than just a knock sensor.

The engine light is not glowing ; will it still show some codes??? And this is a city mileage....i havent checked highway though

E Meyer wrote:

18 mpg a little low, but its not totally out of line for stop & go driving in the winter. If the knock sensor is the only code set, it does not turn on the engine light. If you check the codes, it will show the knock sensor code if its set even though the engine light is not on.

Classic symptom of a failing coolant temp sensor. Happened on my wife's Altima and my previous Maxima. Replace it. There may be 2. One is for the temp gage and the other reports to the CPU. Replace the CPU one. On the Maxima I beleive it's one of the sensors around the thermostat housing.

CD

18 in town in the winter is about correct. 26 to maybe 28 on the highway at 65 mph constant.

almost spot on with the epa numbers btw

But hasn't it come out lately that the EPA numbers are, to put it chnaritably, "optimistic"?

yes,,,

thus if you are getting them you are doing very well.

any specific reasons why the car has a lot of smoke in the winter mornings???

Though i see most of the cars with it(except the big trucks)--- is it an alarm??? Thanks,

-Manish comm>

my '87 maxima GXE was getting around 18MPG when i bought it for $400.00 in the spring of 2005 and as i drove the car, the gas mileage got worse and It finally got so bad the motor would not idle with the a/c on. I didn't know much about the car at the time, but going off of the motor misfiring, I felt that it could use a new set of NGKs, after installing the new plugs and an air filter, the motor ran a lot better, it would Idle with the A/C on after that and it got around 23MPG. I later put a new fuel filter on it and it bumped it up to 25MPG. The struts on the back were in really bad shape, so I installed new struts. I had the T-belt changed along with a new tensioner, thermostat and a water pump and I run the tires at 40P.S.I and on the highway I can get 33MPG. Just try a basic tune up(If you haven't already) and see if that helps.

maxima '87 max GXE 125,000 miles.