...how do you do it? I have a '99 5.9l 4x4 with 3:55 gears, stock size tires, and 127,000 miles. Nothing is wrong with my truck as far as I know. No plenum leak, no clogged cat, no death flash, and she got a complete tune up a year ago, I have a superchips 3815 set to tow mode, and my truck is an absolute DOG when towing.
Last night I had to make a 150 mile round trip to pick up a snowmobile. I used my uncles 10' single axle trailer which weighs a little over 800lbs unloaded. It is a very free rolling trailer.
I know that it is not good to tow with overdrive turned on, but I figured with a tiny unloaded trailer like this I'd be ok. WRONG. On perfectly level highway I couldn't maintain 70mph at all. I had to run with OD off just to maintain a legal highway speed which means I was pulling 2900 rpms for over 150 miles. I got 8.5 mpg as a result. What gives? For those of you who tow with your dodge regularly, how do you deal with this? I know 4:10 or 4:56 gears would help a lot, but c'mon! I have the friggen towing package for crying out loud! You'd think I'd be able to tow at least 1000lbs without too much trouble!

End rant.

 

you sure about that plenum?

 

same thought here.... i pulled my harley on a single axle with no prolems.. blew the trans but the first 200 miles couldnt tell the trailer was even their

 

+1 on the plenum... I have the Same tuner.. and had a tune up 1.5 years ago and I can pull my 6x12 tandem that weights over 1,500 empty at 70mph in OD on a flat highway... I always pull with OD turned off when loaded.. city driving.. or hilly area... also when merging onto a freeway... I would seriously check your plenum. You shouldn't even notice a trailer like that.. also.. the SC tuner will make your throttle pedal respond differently.. (i.e. it will make the truck downshift sooner) I'm sure you found that speacial spot right between downshifting and giving it as much pedal as you can before it downshifts.. if that makes cense

my new homebuilt trailer


10,500# mini excavator and 1,800# trailer

 

yep, you losing power someplace. I regularly fished bass tourney's all over the southeast from the early '90s till about 2001. Used a Furd diesel and a POS '97 Furd F150 4x4 (most of you have read about my engine going bye-bye with 14k on it whilst trailering back from Lake Sinclair), up until late fall of '97 when I bought a new '98 Dodge RCSB 5.9 4x4.
Even with a lift and over-size tires it towed my 19' bass boat, trailer, heavy a$$ 175 HP motor and a slew of gear with no issue whatsoever. Only performance mods on the 5.9 was a true duel exhaust and headers. My gears were even the crappy 3.55 factory ones...

Towed this 17' with a 140 HP on it from the time I bought the Dodge till '99:



and this much heavier boat from spring of '99 :

 

Mine tows my 3000lb double axle horse trailer with a full grown horse just fine. Way I see it, 3k trailer and 1500 lbs quarter horse = 4500lbs every weekend and it pulls it with ease and i've got 3.55 gears on 32" tires. Dont know what to say to you man.

 

Just for kicks, put your stock tune back in and see how it tows.

I'd have to believe with a plenum leak and that tuner she'd ping pretty bad.

 

i pulled my 16 foot fishing boat with 35" tires and 3.55 gears and really didnt notice much of a difference and that is with the stock gears with 35s!

 

ok but what was every one getting for gas milage too. he is also getting less then 10 miles to the gallon...

 

Thanks for the replies. I guess there might be something wrong with my truck. I replaced the plenum with a hughes kit. Last time I looked down the TB I didn't see any oil, and I'm getting no spark knock. But I'll do a vacuum test whenever I get around to it just to be sure.
The mods I have so far include 14x3 air hat, 180* tstat (soon to be changed back to stock), 3815 tuner, autolite 3923 spark plugs, magnaflow high flow cat, and a flowmaster muffler.
I haven't checked the spark plugs since I changed them last November, but I'm getting decent mileage (when not towing) and she runs/idles like a top.
Do you think the 14x3 air hat could have something to do with it? I think I'm gonna change it back to stock just for kicks.
Any other ideas? The truck runs great, she just sucks at towing.