I posted on here a few days ago about my 93 getting 9mpg, well the only sensor i haven't replaced was the o2 sensor and i was wondering could this be causing my 9mpg even if the check engine light isn't on? checked for codes and none are stored. I also put my stock air cleaner back on and took the open air element one off. Come on fella's I need to get this figured out, I love the little truck but if all i'm going to get is 9 or 10mpg it has to go, heck i know its a truck, a 4x4 with a 5.2, I would be happy with the 12-14mpg range in the cold weather. Thanks again for everyone's input on my never ending quest on trying to figure this thing out.

 

Yes the oxygen sensor can cause poor gas mileage even with out a check engine light. Just replace it.

 

I think i will pick one up tommarrow, any brand suggestions? all the rest of the sensors i replaced are standard part brand, except for the map that's a delphi. Thanks again for the help guys, it is appreciated!

 

myne shorted out and caused huge issues and i never had a light either. so i'd go for it.
also have you checked to see if your plenum gasket is blown? that can cause issues aswell

 

I looked down into the plenum today and its alittle oily, nothing really bad, no oil pools. My truck hasn't been using excessive amounts of oil or been pinging. Thanks again fella's!