2nd Gen Non-Engine/Transmission What happened?????

[RussW1911]

What happened to my mileage???

My mileage took a crap on me this weekend. On the same route towing the same trailer driving the same way I always do, I averaged 12. 3 mpg. I was getting 16. 7 previously and 20. 4 empty yes, hand calculated. Not just one tank, but 3 tanks in a row I couldn't break 13 mpg the whole time. We could have driven my dads 1993 1/2 ton gasser and got that.



I never lugged the engine. No cruise control. Freeway driving at 1800-1850 cruising. Shifting at 2200. Fresh Fuel filter w/ less than 1000 miles on it. Unless someone snuck a softball in my straight pipe thats not clogged up. Looked for Boost leaks and couldn't find any. 15-16 psi at idle and 10-11 cruising at 63mph. Check my sig for minor upgrades. Don't have any power upgrades yet. EGT's and Boost seemed normal.



As for major changes... ... I just put on BFG AT's but they are the same size as stock. The other change is that these are the first 3 tanks of fuel I have put Howes meaner cleaner in. Could this be the cause of it all. The truck runs quite a bit smoother and doesn't have the high pitched bark at about 2000 rpm like it used to. No loss of power either.



Any help would be greatly appreciated. I drive this route a lot and need the mileage. Russ

 

[rashwor]

Thoughts.

Dirty fuel filter. Bad load of fuel. Dirty air filter. Change filters and fill up somewhere else next time.

 

[RussW1911]

Already have a fresh fuel filter, fresh oil filter, fresh air filter, got fuel at 3 different stations on the trip. Did a full service at 30,000 miles just before the trip. Only thing I changed was that I started putting in the Howes additive this time. Also, I only fuel up at big Truck stops on busy freeways to keep fresh fuel in the truck.

 

[RussW1911]

Thought I would get more info that this... ... .

 

[jponder]

ait might be bad

 

[RussW1911]

Will Check

I will check the sensor after I get off work. Thanks

 

[jkern]

head wind??? drops mileage more than you may think

 

[RussW1911]

Checked sensor...

I checked the sensor tonight and the white part was barely discolored. I cleaned it anyway and reinstalled.



I was hoping that it was the headwind as well, but I got about the same even when the wind was from the rear. MPG's dropped when empty as well.

 

[RussW1911]

BTW

I am only towing 4-5k. Not a big load at all. Just a small travel trailer. That guestimate is even on the heavyside.

 

[RBSOB]

Russ, did you go from a highway type tire like stock Michelins to the new BFG ATs? I run "winter" aggressive tread tires and Michelin highway treads in summer, about 2 mpg penalty with the winter tires but it's a necessary trade off. Anyone else notice this, the Michelins seem to have a much lower rolling resistance [they also allow more "wander"] on my truck? JimG.

 

[RussW1911]

I did go to the new AT. The michelins were garbage and the company would not stand behind them. They were rotting out, I guess from the sun. I didn't think that the BFG's would cause me to lose 4+ MPG though

 

[y-knot]

I don't no I have a set of BFG's and they are a very heavy tire, maybe the larger un-sprung rotating mass had more to do with it then you think?

 

[TboneMan]

What pressure did you have the BFG's at. Those are only load D's (max 65psi).



Take all of these factors into consideration and add a head wind and you might end up with less mileage.

 

[RussW1911]

Tire Pressure....

I keep the front at 65 psi and the back at 55-60 psi depending on load. I am hoping this is not the problem. I will be adding injectors and a fueling box soon. Maybe that will help.