I'm Currently not getting very good gas millage so I had a scan ran on the truck there was no trouble codes. Which was good but still trying to figure out why bad MPG and I had a tune up maybe 2,000 miles or less ago. There is some black soot coming from the tail pipe.So I was thinking could it be bad O2 Sensors or something else?

 

what was all done on the tuneup?

clean maf sensor throttle body?

 

Cleaned maf, Oil change, fuel filter, Spark plugs and wires, Air filter. I didn't clean the IAC which i shoulda have done.

 

Anyone else have ideas?

 

unplug 1 02 at a time and drive it, see if it throws any codes... also just because there are now visible codes, doesnt mean there are no stored codes...

 

also, spend the 5 bucks on your pcv valve... kinda goes with a tune up

 

Okay and where is that located?

 

How "bad" is bad -- I'm seein 33" tires and 7" of more air -- below 13mpg-indicated or ??

Could be worth a look at the t-stat /coolant too -- if your CTS diesn't show operating temp, you'll live in the richer end of the map -- this butt-assed cold weather can help that to show up too.

 

There is a PCM update for this. Get it done at the dealer and the MPG could be from the cold. thats what ford told me

 

this man is correct. over size tires, lifted. the trucks only rated 14mpg with the 4.0 auto stock so don't complain.

 

If your saying I'm complaining I'm not. I'm just seeing if there could be an reasons for the bad mpg because i know people that are getting better with my same set up.

 

if you do city, regear your truck. dont giver off a stop. and keep your foot off the floor.

im getting 15 mpg with 235/75 tires. buck up

 

well i bought a Sct tuner And im getting 15mpg right now on my performance tune

 

That seems decent for being lifted with a heavy tire/wheel combo. I can manage 20mpg/a tad more or less on how I drive, that's stock 31's and driving the speed limit.

 

you've also gotta think that your higher up so atmosphere is affecting this too.