have 9 dodoge ram 2wd 1/2 ton club cab long bed (i think) trailer package and auto with 318 motor what should be average fuel economy i am getting 13mpg on the hiway (O2 sensor is out )any suggestions on where to strat to improve it also performance could be better only has 159 ,000 on it

 

Um... o2 sensor.

 

Wow, that sucks.. i get 19ish from my 4.7L 01 dakota 4x4 quad cab w/ 175k..

O2 will make a difference, change the oil and air filter, check the tire pressure, drive slower? dont run the a/c.. lol

 

The AC in newer cars doesn't affect mileage THAT much. It only robs a few ponies to operate

 

Get a new 02 sensor...Without it the motor richens up...13 isnt out of the normal range...I have an 03 Durango r/t and I did everything to it to get better mileage and it wont do better than 13-14

 

i average 2mpg less if i run the a/c..

 

Dont be so fast to throw a new a new O2 sensor at it. If that is just popping-up as a generic code, than that can just mean that the O2 is seeing something it doesn't like! If this was diagnosed at Autozone with their $100 sensor, I would be very apprehensive to change it! Better scan tools "dig-down" into the faults and will tell you things like "cylinder #3 misfire". That can cause increased hydrocarbons from that cylinder[that the O2 sensor WILL see], and in turn, cause a fault FROM, BUT NOT OF the O2 sensor. I have 2 Chryslers with 3 O2's on them each, 250k on both, and they STILL have the original O2 sensors. I just feel that these are "over-changed", and over-blamed. Have you tried the "key-trick"? Turn the key on-off-on-off-on, it will then flash the check engine light in a code, or display the standardized OBD2 fault codes in the digital odometer read out [if you have digital odometer].

 

The O2 sensor is physically out or is just not reading? If it is physically out, then put it back in or put a new one back in. If it is not reading, then it could be the issue, you could have a bad/broken up cat that damaged the O2 or like Scotty said you may have a cylinder (or more) misfiring or an injector that is stuck open too long.

When was the last time you did a tune up? The Magnum motors (3.9, 5.2 and 5.9) like to be tuned every 30,000 miles on a regular basis. Failure to do so causes issues like this. Also, how much carbon build-up do you have in the throttle body and intake? You may want to spend the better part of a day cleaning the throttle body, running a fuel treatment cleaner through the fuel system and performing a tune-up right after figuring out why your O2 sensor is "out".

 

The way i read it was he had no o2 sensor, which, was stupid on my part. Cause it wouldn't run for crap without one..

The best way to check to see if the o2 sensor is truly out is to take a DVOM and measure the voltage that is getting to it while cold and running. It'll tell you if you're running rich, lean, ect.

I'm not sure what the voltage spec on it is though.

 

On most of the Chryslers, Dodges and Jeeps that I have worked on (even on those other lesser quality makes - LOL) it's been 0 to 5 volts.