Thread: Horrid mpg what am i missing???

My mpg is sitting at like 17 mpg on the d.i.c Ive changed oil changed plugs changed wires put on a new fuel filter new airfilter too
swaped blowers due to a bad coupler and it being pretty chewed up
Even clay bard and waxed to bring down wind resistance..(j/k)

the car has 179xxx on it

No codes runs decent ill say
has minor oil leaks i have yet to fix

I have a pc based diagnostic program
not quite sure what to look for what normal paramiters are for these cars

Any input would be great
its sad that my crown vic is getting better mpg with a bad maf and cats that are beging to fail

Could have a bad o2 sensor.....maybe?, I bought a replacement for mine just have not changed it yet....They say a bad o2 sensor will set off the SES light but I'm not totally convinced it will. What year is your car?
Try disconnecting the battery for a while it might be something with the PCM.
Have you done a Seafoam? You should do that before you cance the oil, the plugs should be ok after the Seafoam since they are new.

havent seafoamed yet
its a 98
the o2s look ok from what the data logging shows

good to know

If you do the Seafoam make sure you do it outside and not inside a garage cause it smokes and stinks like Hell.

Originally Posted by BwolfGT

I also have a 98 GT, I thought my 17MPG was normal is that bad for our cars? lol.

yea my gtp is always reading around 15.6 on the DIC... i would think you are lucky with getting 17

I've been upset with mine at ~23, and that's with bigger brakes, 17" wheels, wider tires, etc. I was getting 30+ when it was newer.

Originally Posted by BwolfGT

Try fuel injector cleanor...mine read 15.6 for months till I ran that through a few times, now it's jumped to 17

yea i seafoamed the car a little while back, didnt change

MAF Cleaner? Have you done that?

Havent cleaned the maf yet Is it built into the throttlebody on these cars
i Have done seafoam treatments before just not on the gtp

I dont know I thought the gps got atleast 20-25ish mpg

I guess I should have said the MAF sensor instead of just MAF, yes that's where mine is located. There are two security screws (torx) I think, that secure the sensor to the TB. Disconnect the wiring harness and use MAF Sensor Cleaner to clean it. Don't touch the wires inside the sensor just spray it down real good and it dries pretty quickly.
If you use an oiled air filter like K&N, the oil will goof up the sensor so you should clean it every once in a while.
I think NAPA, Sears or parts stores will sell the security bit.

Heh...I got 31mpg's on all of my mods with a custom tune and a 3.1" and the stock tranny...hell even with my misfire and only running on 5 cylinders I was able to squeeze 19mpg out of it on the HWY

What kind of gas do you use? just wondering

supreme at chevron usually
but nothing less then 91 octane

o2 sensor...fuel filter...plugs/wires...air filter...do that stuff

Originally Posted by bluegtp91

o2 sensor...fuel filter...plugs/wires...air filter...do that stuff

yea i gotta do that stuff as well. its on the "To Buy" list