Just got back from a trip to Las Vegas.. Boy am I ******!!! First tank 14.8, second.15.9/// .. The best was a 100 plus mile stint where I hit 20.8... Then 13.97... and finally 18.87!!! What in the heck is going on??? Why is the fuel mileage all over the place???

 

Idling
Jackrabbit start stops
Speed
Wind

Mine is sitting on 23.4 right now, usually hand calculates right at 20 for the tank.

 

On mine, I've noticed a gain or loss in elevation will make a difference, as will wind, but road speed makes a huge difference.

 

This is ALL HIWAY miles... No jackrabbit starts, no driving 100 mph, etc... Altitude should account for 1 to 2 mpg .... along with wind.. BUT NOT A 7 MPG difference!!!

 

...and idling. Try hitting the reset button on the overhead display while coasting down a hill the display shows 30 or miles MPG. Idling for just seconds causes that display to fall like a rock.
Nat

 

Falcon... Is that hand calculated??
Once you break 68 mph the milage seems to drop pretty quick. I'm getting a steady 15.5-16mpg with winter fuel and now 17.5 with Stanadyne added to each tankfull, but hand calulated and steady driving has very little variation with my calculations each tankfull. The overhead on mine reads + 1 mpg.

 

Mine is all over the place as well. There is no consistancy to it. Now with winter fuel and more ideling it is in the crapper. I have just accepted that it is the nature of the beast. I dont like it but I cant find a way to get the milage to repeat. I can get anywhere from 13-14 all the way up to just abought 21 with not much in the way of noticable driving diferences. I have been keeping a fuel log now for abought 6-7000 miles. I hand calculate every tank and the numbers are all over the place. The one time it realy chapped my rear was last June on our vacation to Colorado. 2000 mile round trip pulling a 6x10 flat trailer with 2 ATVs on it. Driving 68-72 with the cruse set it only got 12 mpg . That is flat out unacceptable. That truck litteraly should have never know that trailer was back there. I had a 2000 GMC z71 that would have blown that milage out of the watter pulling that little trailer at a higher speed.

 

Like I have been saying, the diesel fuel quality is all over the map. I think it is the worst I have ever seen it. Not everyone is playing by the same rules.

 

Highway speed seems to be the biggest mileage killer for me (after repeated city jackrabbit starts). But I have also noticed that after working it hard on a trip the mileage increases for a while . Can't figure that one out.
Anything over 70 starts to really take a toll on mileage.

Wetspirit

 

Yes,,, All hand calculated.. The OTC is sometimes under and sometimes over. and rarely, close to right on... Something is causing the mileage to be about as wild as a teenager on his first date...

 

falcondan,

On a non related subject, How's the snow over your way? I'll be in town next week. Thanks



Wetspirit

 

I too have recently noticed a decline in my mileage. I have the exact same truck as you and I too am aggrevated. I was averaging about 14.5-15 mpg a month ago. The it seems as though the fuel quality just got worse once the prices started to decrease. So one thinks "great fuel prices are dropping" but, the fuel quality is degraded so you'll actually be spending more @ the pumps. Time for some after market toyz.

 

The weather here has been very nasty... Snow Snow and more Snow... Last night it started raining, bad ju ju...!!! But I believe it is snowing again and going to keep on thru Monday...

 

4 feet of snow in my yard and still coming

 

I wonder if people driving Ford and Chevys are noticing a significant decrease in mileage? It is an intresting concept that the Diesel may not be as "good". Yesterday I experianced around a 2 mpg decrease in mileage on my normal 50 mile trip. If I drive 65 and reset the computer when I leave I can normally hit 19.2 mpg at the end of 50 miles. Yesterday it was around 17.2. By the way I haven't had the reflash and still am debating if I should get it. Oh by the way...last time I check my over head trip computer accuracy it was dead on.