Towing Mileage Dropping

[Parshal]

I know I've complained about this before but I'm a bit miffed at the moment. I just came back from a 900 mile round trip towing my 4k TT. Let me start off by saying that my first 900 mile trip averaged 12. 4 mpg at around 70 mph using cruise control. That was late January when I had around 14k miles. My last trip a month ago I averaged around 11. 5 mpg (lowest was 8. 5). I changed settings on the EZ from 1 to 4 along the way and checked the mileage for each setting. The best was at level 3. I used cruise for most of the trip.



I had raised the trailer 2 inches to have it sit more level as adding a lower trunnion would reduce the clearance to less than 10 inches. This was done prior to the last trip. When the mileage dropped on that trip I lowered the trailer to it's original height after studying the mileage spreadsheet that someone posted here. On this trip the best mileage I got was 11. 9 with no wind at 73 mph and that was on level 3 without cruise control. I removed the EZ completely and got just under 9 mpg.



What's going on here? I now have 22k miles and I'm seeing the mileage drop when towing. I can see it dropping if I were bucking a 20 mph headwind the entire way but this has not been the case. I'm getting fairly peeved as I expected better mileage than this.

 

[coonrod70]

Milage

Just curious, do you tow with the overdrive on or off? I have done some limited towing(100 miles round trip) interstate driving with about the same weight as you and am getting 13. 5-14. I towed with O. D. off. RPM's run about 2600 at 65-70 mph. Mine only has 1600 miles on the truck, though. I was hoping to see the milage go up but maybe it won't!! Running empty on the same roads I'm getting 17.

 

[JohndeereG]

Originally posted by Parshal

On this trip the best mileage I got was 11. 9 with no wind at 73 mph and that was on level 3 without cruise control. I removed the EZ completely and got just under 9 mpg.

Are you checking your milage via the overhead display or is the old fashion pen/paper? I remember reading a post not to long ago of how an aftermarket device like the EZ will give inaccurate readings on the overhead.



I towed my 49 John Deere G farm tractor yesterday for the first time. Trailer/tractor gross was around 9K. My overhead display gave me a reading of 11. 7mpg. (78 mile trip) I have found my read out to be within +/- . 2 Overall I was fairly pleased considering I was traveling 30 miles of the trip over some rather long/steep Pennsylvania hills.



Parshal what is your average mpg unloaded. [Pen/Paper] I average 18. 3-19. 3 on regular roads with up to 20. 7 on highway traveling. I like to stay around 2K rpm when shifting and cruising. (Just trying to get a feel for how our driving styles compare)

 

[Parshal]

Re: Milage

Originally posted by coonrod70

Just curious, do you tow with the overdrive on or off?

I have the 5 speed manual transmission.

 

[Parshal]

Re: Re: Towing Mileage Dropping

No, it's with pen and paper. I've checked every tank with a calculator since I bought the truck. Unfortunately, I just started writing it down when I noticed it dropped. With the EZ, the overhead consistently reports 2 to 2. 5 mpg better than actual.



I get 18. 1 with the EZ on level 2 and 18. 7 on level 3 driving unloaded. I have gotten over 20 on three occasions one being 22. 2. I usually shift around 2000 or 2100. I noticed that I get around the same mileage if I drive it very hard racing every gear from each stop. Amazingly, that has no effect.



I can't figure out how my towing mileage is so bad. I realize wind resistance has more effect on mileage than weight but my trailer is fairly small compared to others even though it has the aerodynamics of a cinder block. Heck, a 15k tractor can't be more aerodynamic than my camper.

 

[DIESELMAN]

After 8000 towing 7400lbs behind mine, before the EZ03, 15. 4MPG, 13. 8 on the computer, only my tires screw up the readings. I drive easy, shift around 2. 2K, 60-65 avg. Unloaded I get upwards to 19. 2 calc'd, once it has broke 20 over a full tank, average over 20K is now about 16. 8.

 

[Parshal]

Originally posted by DIESELMAN

After 8000 towing 7400lbs behind mine

What are you towing that's 7400 lbs. ?



I also added 10 lbs. of air all around before towing as that usually makes a difference and it didn't do a thing. I'm running 55 in the front and 54 in the back both cold readings. The first two long trips were at 45 all around.



I've removed the EZ this morning and will remove the boost elbow this evening. I run the EZ on level 3 and, after removing the box this morning, I can't tell it's gone. It feels like it has the same power. Very strange.