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Discussion Starter #1
I've got an 02 3500 dually and we've only used it to tow our larger trailer a couple of times since we got it a couple of months ago. I'm not really sure what to expect, but it seems weak to me. Am I expecting too much? Honestly, most of my experience has been with an 04 Ford 6.0. Got the chevy figuring the long term reliability would have a better outlook.

Our 5th wheel is about 12k & 36ft. On flat ground it'll cruise at 65-70mph, but accelerating much at all goes to downshift & redline while it slowly if at all accellerates. I'm afraid of what it'll do in the mountains or with a heavier load. Our 6.0 would hit 80mph before you knew it and had to back off. I expected it to be a little less than the 6.0, but not like this.

changed the fuel filter (made it a little better), cleaned the K&N. Fuel injectors were replaced 10k miles ago. No smoke.

Taking it to the dealer today to check out a coolant leak, but thinking of just selling it. Right now, our 5.4gas work truck will tow the 5th wheel almost as well.

Any thoughts? What's y'alls experience with downshifting & accellerating with a load?
 

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How many miles on it? Any rough idle, hard start, or fuel in the oil?
Any sign of head gasket trouble?

I would ditch the K&N and go back to stock. Could have dirty or oily MAF from it causing some loss of power. (search in the fuel system forum for air filter discussions). Get some CRC MAF cleaner and try that.

Stock tune? Get a PPE excellerator, even the economy tune one, and it will wake that DMax up. With mine of level 2, the difference towing my gooseneck horse trailer is well worth it.
 

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Since you have a K&N filter, I'll make the suggestion to check your Mass Air Flow Sensor. I had problems with oil on mine and have since switched to a Wix filter. Still has good flow ratings, but better dirt stopping power and no oil on the sensor. The MAF is one of the easiest places to start. And your power symptoms seem to fit.
 

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Discussion Starter #4
I too hate the K&N, but it was on there and I didn't have a stock setup. I tried a stock like filter on the K&N tube for our trip to florida recently... no difference. I did clean the MF, but didn't replace it.

No codes. 153k on truck. No fuel in the oil that I can see from the paper towel test. Level stays pretty constant.

I do have a coolant leak that leaks quite a bit when above 2000rpm. It drips/runs down mostly from above the bell housing down over the oil filter.

Starts instantly. No smoke. In fact it runs decent empty so I never noticed it until we installed our gooseneck & 5th hitch to start hooking up to the trailers. Now I guess I missed something when we bought it.

I'll buy a new filter setup if we keep the truck, but right now I just can't imagine any of the big 3 towing this weakly on a diesel, but maybe I'm used to a different running diesel.

I wouldn't even mind a tuner, but just don't want to drop any money in it on performance stuff unless I know that the truck is running right.

Anyone towed with both a ford and a chevy?
 

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i agree with sparky. the ppe does amazing things. The intake and exhaust, and a tuner are the first things i would recommend with any duramax.
 

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There's got to be something missing. I pull 13k with no problem, and did so even before the six gun. It's just wasn't as easy. Somebody on here will have some good ideas, I'm sure of it.
 

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Discussion Starter #7
I'm all for a tuner, but I just can't spend more money until I know if there is something actually wrong with the truck. I don't trust the dealer much to tell me, but we'll see what he says. It doesn't feel anywhere near what I expected and I'm wondering if there's a problem with the boost or fuel...
 

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Did you check the boost tube off the turbo down to the intercooler for a rub hole? There have been lots of posts on that lately.

The coolant leak is probably coming from one of the hoses on the turbo.
 

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My 02 runs up big grades at speed limit with 10,000lbs . Yes it'll downshift as needed but keeps pulling/accelerating. Check those ic hoses for leaks.
 

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Discussion Starter #10
I've done some looking for leaks, but haven't seen anything. I did check the driver's side tube pretty close where I read there had been rubs.

I got it a the dealer now to look at the coolant leak. We'll see what comes of that.

I did clamp the waste gate tube to see if it ran a little stronger since I don't have much to work with like a boost gage or something to compare to except the ford. It seemed stronger (unloaded). However, when I took the vice grips off, it really didn't run any different (unloaded still). Makes me wonder if the waste gate is sticking and if now it's sticking closed instead of open.

To me the power issue or lack there of is above 2000rpm. It does pretty well lugging around below that, but not much of extra above it.

thanks for the feedback on others towing. It's hard to imagine that what I got is the norm.
 

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when I would hook on to a 40' sundowner w/interior on a stock tune my truck would run like yours on the bottom end. It would move out up to about 2k like you said, but then it would take forever to get into 5th on the freeway. I modded the air box, put the 4" magnaflow on and got my programmer, and I have'nt had a problem since.
 

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I pull a two car hauler with my 2001 dually. I have a Preditor set at 65 hp and this thing will pull a house. I just puller Mount Eagle in Tenn. (5% grade for 5 miles, run away truck ramps on the down side) with two cars ( truck, trailer and cargo I crossed the scales at 21,503 lbs) and it down shifted to 4th but I go up it at 60 mph and only threw 16 lbs of boost at it to do it (so its got a lot left) Exhaust temps at the 850 range so its not working very hard. The tuner sure did wake this up. But I feel you must have something holding you back.
 

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Discussion Starter #13
Looks like I'm going to stick it out and make it run. It already has 4in exhaust and a K&N. I'm not a K&N fan so need to switch something there.

Any thoughts on a nice, simple relatively inexpensive tuner/programmer? All this truck is ever used for is towing... other than that it's parked.
 

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the Ford 6.0 makes more power then the 02 duramax. Get a boost gauge, and a pyro. That will tell you how the turbo is doing / boost leaks, and is you are under fueling. if all looks good, get a tuner. You should be good for 100+hp over stock on a 02 before the allison starts getting grumpy.

Anybody know the hp / torque specs for each stock? lb7 lly lbz lmm?
 

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Discussion Starter #15
Thanks. I'm hoping a mild program will wake it up like the old Ford 7.3.

Will go for the gauges & a program and will go from there.
 

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my 2003 dually (which is the same motor as your 02) pulls 28k combined up hills no problem. from sacramento to salt lake city which starts at sea level and exceeds 7900ft and down and up, etc. a good tow tune like the one from Nick (vortecfcar on here) helped a lot, as did cleaning my radiator. i was having overheating problems which stemmed from teh radiator being full of feathers, hay, and mud.

stock they are somewhat slow. just keep whatever tune you chose to a mild one and you'll be very surprised.
 

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Crash1068 I have been having the same probs for some time now, and I only tow a 8k camper. I think my 5.3 gasser before would tow it much better. Still never found a prob, evrything I have been told to check for is up to par. All I can think of is trading it in, it runs decent unloaded but horrible with a camper behind it. Once the torque converter locks in 5th there is nothing there whatsoever.

Forgot to mention my egt's run about 1100* too which is rediculous. Thats on level 1 too !! My truck is jacked up..............
 

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Discussion Starter #19
Put a Van Aaken box on purchased off ebay... made all the difference in the world. With the switch set at 70hp, it's about on par with my old 6.0 ford and a little stronger on the bottom than the ford. On the 110hp setting it's noticably stronger than the stock 6.0. I'm pretty much just leaving it on 70hp for towing.

Leaving for a long trip with 16k tomorrow so we'll get a good check out. So far on short hauls around town, it's made the truck feel like a whole new rig. I really would have sold it without the box!
 
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