Need help

mcreyaufmiller · August 2, 2005

Here's the deal:

New plugs (Bosch P2) MSD wires, clean air filter, fresh oil change (mobil 1), new upstream o2 sensors.

I am getting about 13 mpg as measured tonight down from 19 2 months ago. I have been getting bad milage for a while, but due to pulling a trailer with my old truck on it, I have not been keeping track until this weekend. Now I measured this terrible milage and am trying to figure out why. I would be greatful for any help.

Bish · August 2, 2005

Here's the deal:
New plugs (Bosch P2) MSD wires, clean air filter, fresh oil change (mobil 1), new upstream o2 sensors.

I am getting about 13 mpg as measured tonight down from 19 2 months ago. I have been getting bad milage for a while, but due to pulling a trailer with my old truck on it, I have not been keeping track until this weekend. Now I measured this terrible milage and am trying to figure out why. I would be greatful for any help.

<{POST_SNAPBACK}>

Wow, that's a pretty good drop. You sure you don't still have a trailer back there

You hit the o2 sensors which would have been my first guess. Nothing else obvious. Did you rest the computer after the o2 sensors? My mileage didn't go up until I pulled the battery cable for 30 minutes to clear the "learning" computer. Worth a shot. I only lost around 2mpg when my o2's were bad. I don't think it would explain a 6mpg drop though. Maybe the torque converter is not locking? Fuel filter, pvc, bad fan clutch (engaged all the time)?? Alternator bearings draggins? I'm running out of guesses...

sxmax · August 2, 2005

If you still have your cats which I am sure you do check to make sure one or both are not plugged. That will make for really poor gas mileage.

asilverblazer · August 2, 2005

Would a difference in readings between the new upstream O2 sensors and the old downstream O2 sensors cause this? (A difference beyond the normal)

mcreyaufmiller · August 2, 2005

cats are not clogged, lots of flow there. I did not think about the PCV, I will have to change that. I am not sure about the difference between a new upstream and a old downstream, any techs out there that can give a clue on that one. I did close the airbox back up, that has been open trying to get more airflow. I am thinking that the heated air from the motor may have been causing a drop in the milage.