Took my truck and trailer (trailer rated for 14000kg) and drove 3.5 hours to pick up a backhoe attachment, drove back. Filled up and checked my mileage and was very dissapointed to see the result! 11.6 mpg

LoL...sorry , 14 000 lbs, 16 inch tires. I always use a trailer from a friend of mine, this day was a different trailer from another friend also.

I'm going to assume it is a flatbed and assume it weighs 4-5k lbs when you were getting 11.6mpg. If that is the case, yes you should be getting around 14.

what size tires are you running. and are you compensating for that in your mileage calculations.even empty i calculate an average of 15 mpg on and off freeways and in town. that is without compensating for tires.but with my speedometer reading 65 when my actual speed is 60 I am running an actual 16.25 mpg when i calculate 15mpg going off of the odometer/gallons usedits not a huge difference but its something and the larger off stock size you are the more your calculation is going to be off.. i too am disappointed however with my mileage.. without a trailer my mpg's should be at least 18

I don't want to hijack this but Johnfak I read a post you put in the MPG fooler thread about how you're getting 2-3 mpg less without your Edge juice. How did you do that? I am getting terrible mileage with my Comp. Last tank worked out to 9.8:cry: I am running a tank with the comp off and the overhead is showing 10.9 now. This is getting really hard on the pocket book:nono:

I don't want to hijack this but Johnfak I read a post you put in the MPG fooler thread about how you're getting 2-3 mpg less without your Edge juice. How did you do that? I am getting terrible mileage with my Comp. Last tank worked out to 9.8:cry: I am running a tank with the comp off and the overhead is showing 10.9 now. This is getting really hard on the pocket book:nono:

Dunno - most people get a mpg increase due to timing of the boxes I guess I would start out with the obvious - and go from there Tire Size ? Brakes and bearings ok ? Not dragging ? In 2WD ? Front driveshaft spins freely ? No Codes for VP44 (damaged vp44 can no longer advance timing) Fuel as mentioned (#1 or #2) How much stop/start driving and speed ? Do you get a "marked" increase in power with the comp on 5x5 .... and do you run it on this level with the vp44 tapped ? If you have a large power increase and have the vp44 tapped, and run in 5x5 ....... on stock tires without major issues I would expect 17-21 mpg on HWY @60MPH and 12-15 pure city driving. Any figures from just highway driving and answers to questions above ??

I don't want to hijack this but Johnfak I read a post you put in the MPG fooler thread about how you're getting 2-3 mpg less without your Edge juice. How did you do that? I am getting terrible mileage with my Comp. Last tank worked out to 9.8:cry: I am running a tank with the comp off and the overhead is showing 10.9 now. This is getting really hard on the pocket book:nono:

I think the overhead is way off with the comp turned on. I would be doing it by hand either way. Though it would be pretty obvious if you are only getting 300 miles to a tank. Is this mostly in town low speed non lockup TC driving?

Dunno - most people get a mpg increase due to timing of the boxes

I guess I would start out with the obvious - and go from there

Tire Size ? 285/75/16 I know this is part of the problem but does it make more difference in the cold? I lost some mileage in summer but not this bad.

Brakes and bearings ok ? Not dragging ? I haven't actually checked these but would't a dragging brake be hot and smelly?

In 2WD ? Front driveshaft spins freely ? Some 2x and some 4x depending if the road is slippery or not.

No Codes for VP44 (damaged vp44 can no longer advance timing) The only code I've ever had is p1693. When the lift pump died it starved the vp44 so bad that the truck was really bucking and jumping so I expected that it was fried too. I put the Airdog on and there's been no sign of trouble since.

Fuel as mentioned (#1 or #2) #1 fuel

How much stop/start driving and speed ? Quite a bit of this stuff.

Do you get a "marked" increase in power with the comp on 5x5 .... and do you run it on this level with the vp44 tapped ?

I got a huge power increase and yes i run with the pump tapped.

If you have a large power increase and have the vp44 tapped, and run in 5x5 ....... on stock tires without major issues I would expect 17-21 mpg on HWY @60MPH and 12-15 pure city driving.

Any figures from just highway driving and answers to questions above ??

I think the overhead is way off with the comp turned on. I would be doing it by hand either way. Though it would be pretty obvious if you are only getting 300 miles to a tank. Is this mostly in town low speed non lockup TC driving?

The overhead was always bang on before I put in the Comp. Would the Comp turned off still affect the overhead? This is country driving but I'd say what I'm doing would compare pretty close with city driving.

The overhead was always bang on before I put in the Comp. Would the Comp turned off still affect the overhead? This is country driving but I'd say what I'm doing would compare pretty close with city driving.

Yeah - the overhead will be close when stock -> and should say higher than you get when on - eg Mine reads 24 on long highway and I know when I hang calculate it will be 20. Same for city 18->14. Does the truck ever have problems starting or run rough ??? The only thing that stands out on what your saying is *) You get worse mileage with the COMP on {like the timing doesn't advance as it should} *) You had previous lift pump issues. Wondering if you could have damaged the VP44 -> can you scan for codes with a scanner - see if you ever threw a code like P0216 ?? That could result in lower mileage. I don't have much experience with 4x4 + 2x4 driving together with #1 fuel to be able to tell you - but I could see them impacting fuel economy - especially if you never get the truck very arm before you turn off to do some work. The 'key' here seems to be the comp gives you worse mileage - that .. with the lift pump issue is what makes me think maybe something to do with your vp44 - maybe see if you can get a good scanner on it and see if anyone else chimes in on that thought ......