A thought, how is the tranny? Or a possible brake dragging? Could also be the amount of methanol the hippie left wing government makes the gas producers put in, check the label at the pump, if the gas has meth, this is why we use more.

 

its a single tank, the pump up under the cab is the one that went out

 

Suggest that if one or more cylinders is mis-firing - the O2 sensor will increase the fuel to the remaining cylinders since the exhaust gas will be oxygen rich due to the misfiring cylinders not burning - sort of a 'death' spiral on fuel economy.

There is a weak cylinder test that can be done with most standard code readers. In essence, it drops the cylinders out one at a time to see which ones have the least RPM drop - meaning that they aren't firing properly.

For the mileage drop that you state - eliminates things such as fuel blend and moderate changes in driving habits.

 

no draging brakes, the tranny does need to get a filter/fluid change but i didnt think that would do it....could it?

 

its not missing, its not running rich, it actully smells kinda lean i guess

 

For the kind of mileage drop you see - should be able to notice hot brakes or a slipping tranny if these were the cause.

The standard 10% ethanol mix should cause only about a 2-4% drop in mileage. The truck should be choking and puking if E85 were somehow introduced, although the expected mileage drop would be along the lines you're seeing.

Have you tried pulling the computer codes, for grins - just to see if anything has been flagged?

Haven't figured out what it is, but are sure eliminating the possibilities that it's not.

 

do you notice any differences in starting habits...

the 2 wire temp sensor is also the Cold Start sensor and if it goes bad it will consume alot more fuel....

 

nope, starting like always, we always have the 10% crap here, unless i drive about 20 miles to get the unreformulated stuff

 

[quote= the 2 wire temp sensor is also the Cold Start sensor and if it goes bad it will consume alot more fuel....[/quote]

i replaced about a month ago so its good, the temp sensor works fine

 

not yet, but i did unplug the o2 to see if it did anything, i havent taken it out for a drive yet though, ill update on that later tonight