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Discussion Starter #1
All,


I finally had the chance to tow with my duramax to see how it would do, and I gotta tell ya I was a little disappointed. For some reason it only maxes out at 60MPH uphill. My 2003 CC 6.0L with the Hypertech III could hit 75MPH up the same hill. When I am on level ground the D-Max does alot better than my 6.0L just starting out and at lower speed acceleration, but once you hit a hill, theres not much excitement going on. I had it mashed to the floor pulling a 5400lb trailer. Is this normal??? I love this truck, but I expected more from the diesel than 60 with a little trailer. Could someone help me with this....Thanks
 

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Discussion Starter #3
is yours stock??? This thing is an animal on level ground but weak on hills. I just got it 3 weeks ago used. It had 29000 on it and runs great, but it just doesn't like hills.........................
 

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Did you have your overdrive lockout on? Maybe it wouldn't shift into 5th and you were limited by RPM?
 

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Fuel Filter? Something is not right with your truck!
 

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I have found that with my stock truck that if you keep it mashed to the floor, it will not downshift and you slow down. If you let up on the peddle a bit, then it will down shift and you will speed up.
 

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I've pulled 10-12k with mine stock through the hills of East Tennessee and I easily maintained 70-75 MPH. I'm with the "you've got issues with the truck" party.
 

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Discussion Starter #8
It seems like it needs to grab a lower gear. It was spinning about 2200 RPM and not moving. (in TowHaul mode). I took it out of OD but the rpm's were to high. I took it out of TowHaul mode and there was no change. On level ground taking off this thing feels like it will tear the trailer into two pieces. Really good power. Its just the hills that make this thing powerless. Could it be a fuel starvation problem?? Not neccessarily one that would cause the cutting out of the engine under high loads, but just rob it from making any real power under high loads??? Under normal conditions, the truck runs great.
 

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You've got issues for sure, my TT is about the same weight as yours and I have to set cruise control to keep speed LOW enogh to stay out of trouble! I mean if I just use throttle, first thing I know, a glance at speedo shows I'm like pushing 80-85, regardless of hills!


Start with a fuel filter and air filter. If that doesn't do it, then get fuel pump and injectors checked.


But by ALL MEANS, come back and tell us what you find so that we can all share in the solution. Too many times we all offer our ideas and the guy with the oroblem finds the solution, perhaps from our help, and doesn't come back and tell us what he found!
 

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just noticed you have a K&N filter, I would try cleaning the MAF sensor first and foremost. Then go to the fuel filter and air filter. Make sure your basics are ok. After that......how does it run empty? Does it downshift or just run out of power?
 

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My 03, when stock, pulled my 6200 lb travel trailer at 70-75 with no problem. I have hit a few grades in MI that made it work a little but nothing serious. Even with OD locked out you should be able to run up to 70+ MPH. My bets are the fuel filter or an oil-fouled MAF.
 

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GMan915,


I have a CC LB Dually and can easily tow up 6-7% grades at 70+ with my 11K lb enclosed car trailer. That also was with 4 people in truck and AC on. I would say something is not quite right. I agree with DMaxAlliTech, I would check some basics.
 

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<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off">i agree with darin...don't floor the pedal and it shud shift fine...mine pulls my 18' stock trl, 2 ponies and a carriage with NO trbl at all!
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you sure yours has the dmax in it? mine idles up the mountains and through the woods 65 mph juice level 1 4th gear. one of these days ill open it up and see what she can do.
 

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oh yeah forgot i was pulling about 9000#
 

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Discussion Starter #16
UPDATE I changed the fuel filter in it last night and cleaned the MAF Sensor. I pulled the trailer again to see any difference and outside of a little better fuel economy running empty, it still wont do much more than 60MPH on the 6% grade pulling the 5400LBS trailer. My 6.0L pulled the same hill at 75+. Today its going back to the dealer to get a checkup. On level ground this thing runs strong without the trailer, it's just the hills where it shows the problem. I'll let everyone know what the dealer says...Terry
 

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Yes, please let us know what it turns out to be.


Your Max is feeling



My toybox is right about 9K loaded and I can go up our big pass in the area without the truck even breaking a sweat!
 

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Hey, I just thought about this!





Is your brake controller acting up? maybe its dragging the trailer brakes on the hill??
 

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Yeah, there was a post like this some time ago. With them changing the wires around on the plug, the brakes would be on if you were using an old pigtail.


That could be your problem when towing the trailer.
 

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Discussion Starter #20
You have got me thinking about this now.......The dealer has moved my brake controller over to my new truck. But he failed to move the fuse. By default is the brakes applied on camp trailers with electric brakes and the electrical circuit of the trailer brakes releases them??? I wouldn't think so. (big airbrake trucks have the brakes spring applied and pressure released). Any input on this possibility?????
 
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