Hey everyone. My gas mileage over the past couple months has really sucked and seems to be decreasing. I am getting like 10-11mpg on the trip computer in town and like 15-17mpg on the highway. Here are some facts that might help with any suggestions:

- Cap/Rotor just replaced (Napa Echlin parts. Had AC Delco, but corrosion set in less than 6 months after I put them in and the truck became nearly impossible to start)
- Wires/plugs replaced in January (Bosch Wires. AC Delco RapidFire 12 Plugs)
- I use Lucas Upper Cylinder Lubricant every few tanks and use Mobil, Hess or Sunoco Gas
- I have Mobil1 High Mileage oil in the engine and I plan to switch to Royal Purple next oil change
- No Check Engine Light
- Trans shifts fine, fluid is red. Has deep pan/cooler
- A/C hogs alot of power when in use, so I turn it off when I need more power to accelerate. I do feel and hear when it is on. Feels like I am towing something. Freon is fine and I add a bit of oil to it every year when I charge the system (leaks). I didn't use it that much with the past few tanks, so I don't think that it is affecting average mileage much.
- O2 Sensors are probably original. I got this car at 58k and they have not been touched since then.
- These numbers are without excess weight or the roof box on the truck (which doesn't do much to the numbers anyway if any). I don't tow anything.
- All fluids are new or recently changed
- All driving is in 2HI, with the Posi-Lok unlocked
- Tires are properly inflated
- Brakes are not dragging (they were just checked out by 2 mechanics because one rotor was braking warmer than all the others, but not burning).
- Car has Spectre Cold Air intake. Filter was replaced in January with a Spectre 3.5" universal filter with an open filtered bottom.
- Fuel pump is less than a year old, filter is only about 5k old and is scheduled to be changed soon (I do it every other oil change).
-Tires are Goodyear Wrangler Radial P235/75R15 and just over a year old.

So with this information, does anyone have any suggestions (other than anything extreme like not driving the truck or having a 4 cylinder put in) with anything that I can do to improve gas mileage? Should I be replacing other parts like the O2 sensors or coil pack?

 

Lets start by getting an accurate measure of your mileage. The trip computer is not all that accurate. Next time you fill up, stop when the nozzle shuts off the first time. Reset your trip mileage and drive. On the next fill up after that, record the trip mileage and the # of gallons to fill it back up.

Go to the same station for a few tanks, then switch to another station. Gas quality can vary.

As far as suggestions for improvement, there are already too many threads on that topic... Not gonna type out the same stuff listed elsewhere.

 

I use the trip odometer also as a backup measure, and it is very close, if not the same as the trip computer.

I use 3 different stations (different brands) and the mileage is close, probably within 1-1.5mpg.

Ok. I will check. I thought that with all the stuff that has already been done, that I have a unique problem here. Thanks.