Hey folks, I haven't been on here in forever, mainly because my truck sits in the garage all week, only driving it to church on Sunday....(literally). But I bought a 35' travel trailer (bumper pull) back in April so have been putting the truck to more use in the last few months. My questions have to do with RV towing, power, and fuel consumption. I have always towed my 20' car hauler, max load around 8-8.5K, and never had an issue. But with the travel trailer, it's 7.7K dry, so I'm probably pushing the 8-8.2K max loaded. The only change to my truck from what's listed in my sig is the addition of tires & wheels. I'm running Nitto Terra Grapplers, 285/65/18, and if I'm not mistaken they're less than an inch taller than stock. As stated, with the car hauler loaded I never noticed a difference from the stock tires. Here's my issue: Even in mostly stock form my truck runs great as a driver. It does great pulling the car hauler. It does great with the travel trailer up to about 55mph, maybe 60. But when I get on the highway 65-70 it's pulling 20psi boost constantly, more on hills, and the truck just seems weak. EGT is not bad, varies around 760-825 deg. Highest I've seen EGT is around 912. Fuel mileage literally sucks, I'm getting 12mpg (towing) and that's flat ground. Let me clarify: the truck seems weak at highway speeds only. Like I say, up to about 60 it's pretty decent (pulling 10psi boost max), about what I would expect with a 35' trailer. Unloaded, regular highway driving I'm seeing 18mpg max. Best I ever saw in my truck was keeping under 70mph, I logged 24.8mpg, that's tank to tank, doing the math, not the overhead. I realize that with combined towing and unloaded driving it would take a while for the computer to adjust and regain better fuel mileage. But my question is: Is the scenario I described with towing my RV normal for the 2006 5.9? Is she doing what she's supposed to be doing, or do I have some issued beginning to surface? Should I just plan on driving under 65 (don't like that answer)? Are the tires killing me? Oh, I've got 94K miles on the clock. I keep up with the service, Baldwin fuel filter, etc. I've been wondering about wind buffeting and thought about trying an air foil on the roof of the truck. Also thinking about EFI Live, but don't want to toast my stock auto trans. I "think" EFI Live would compensate for the tire size and other parameters and improve the "towing experience", but would it put any of the hardware at risk? The EFI Live guys say they're built to run on a purely stock truck, and guarantee it will not roast anything. Is that my answer? Any comments, input, help greatly appreciated!

 

Can't help much on the towing subject since I don't use mine much for that- by the sounds of it you shouldn't have a boost leak but it wouldn't hurt to double check. May be something small so lower psi does not effect it. With my mods and stock turbo running 70/80mph I'll be spooled at 15psi ish so the additional drag could be hurting you that much. YES to EFI- they can tune your truck with a basically stock setting just tweak timing and some other parameters to help efficiency. You do not have to get a large tune dumping more fuel and pushing more boost- I have the 5 Setting on mine with larger tunes but think it wouldn't hurt to get a 3 tune pack (stock, tow1, and tow 2). As long as you aren't more than 50-75hp over stock and don't drive like a punk you should be fine and will benefit from drivability

 

Time for a built trans. You won't be disappointed.

 

7.7K is a light weight for a 35 foot travel trailer are you sure it doesn't weigh more than that? Did that figure come from a tag or data sheet on the camper? The reason I ask is 35' is a big camper and I would think 10,000lb even as a bumper pull.
What is your RPM on the highway at 70 or so? It's all sounds pretty normal for a heavy load. Keep in mind increasing tire size will lower engine RPM and also cause higher boost and EGT readings at highway speed. Especially if the engine RPM is in the lower ranges of its torque/HP range (engine laboring at low RPM).

PS X 2 on the trans upgrade ASAP

 

Thanks for the replies. I haven't weighed the rig but yes, the data plate puts it at 7700 dry. It's supposed to be half ton towable. I said 35 ft, that's hitch to back bumper. I'm running 2k rpm at 70mph, so it's right on target. Same as unloaded, only I'm at 10-12psi boost unloaded at that speed. Still leaning toward EFI. Trans shifts great but I understand what heat will do to it overy time. Some recommend just a converter. Thoughts on that?

 

Yup EFI AND BUILD THE TRANNY! Goerend TQ and VB and you'll be happy! Give them a call they will only sell you what you need! Just do it right the first time!

 

One must also take into consideration the effect wind drag has when towing a camper. The air foil will help a bit as well as keeping it under 70mph.

 

Did you get EFI yet? Do it! Christmas present to yourself! Also the TQ and VB and your golden for many miles!

 

Should be 2000 rpms at about 75 mph with those tires. Your speedo is off if it has never been adjusted so all the mileage calculations are off also.

The 12 mpg towing is about right, the empty mileage is higher than normal. No way you got 24.8, that was a mis-calc. Even 18 mpg normally is high for a stock truck.

The 5" exhaust is probably causing part of the issue along with the sloppy transmission. About anything you do to the trans and power will make it feel better.

 

The trans will fail if you start adding power. The engine is de- tuned for use in a pickup. You don't need a new trans, just find a good shop, and tell them what you plan on doing to the engine, they'll build the trans accordingly. My son-in-law had one built for less than 2k, and he's pushing 500+ HP. He pulls heavy, 12-14k. No issues. When you do the power adders, your mileage will increase. My 03 gets 14 mpg towing a 14k trailer, 600 HP, 6 speed manual.