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Discussion Starter · #1 ·
Hey everyone, I am new to this site and a newer Duramax owner. I bought an 05 duramax in august, and am having my first issue with my truck. My truck is an 05 ext cab short box, 4x4 with auto, truck has 158k on it, has egr delete and the previous owner cut the muffler off and kept the cat on it. other then that it is stock. my issue with the truck is........it has been driving great since I bought it, but this weekend while I was pulling a trailer about 4k lbs, I have pulled same set up with no issues. It was doing fine until I had to pull a small hill and put my foot in it, in tow haul mode, and then it started to loose power, down shift and stutter real bad, I pulled truck over and looked everything over, didn't see anything wrong. no check engine light on. shut truck down, started it and took off with no issues. about 20 minutes later, same issue. I figured it must have been fuel filter seems how it was getting close to needing to be changed. once I got to where I was going, I unhooked trailer and I went and got a napa fuel filter. truck drove just fine on my way to napa. got back to camp and changed filter. truck drove fine after I changed filter. put some good fuel in tank with some additive hoping it would help. hooked up trailer and headed home. truck seemed to have more power and I thought I fixed the problem. NOPE. second hill I had to pull same thing happened. seemed to do it the worst in tow/haul mode. put it in standard mode and it did ok until I needed more power and had to get over 2000rpm. the truck never threw a CEL. I have not been able to hook up to computer to see if anything was logged. My thinking is it is trans control module or could it be another issue?

Sorry for such a long first post but I wanted to give as much detail as possible.

Thanks in advance everyone!!!!
 

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hello, hard to say with out codes, but good thinking on changing the fuel filter. You could be fuel limping, tranny limping or have a transfer case issue. Very hard to say, as there is no codes and what your describing isnt a typical tranny limp, or the for mentioned either.

Couple of questions.

When was the last time the trans filter was changed?
How is the fluid level in the trans?

Just because the light didnt come one, does not mean it doesn't have a code stored
 

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Find someone with a scanner and check for codes. Like stated already, not all codes throw a CEL. I am assuming it has a tuner of some sort since the EGR is deleted?
 

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Discussion Starter · #4 ·
I don't know about the tuner. i bought the truck from a dealer with the egr delete. I do believe it has the sinister diesel egr delete kit. I have not done anything to the truck beside change oil and fuel filter. The truck drives fine with no issues, until the trailer is behind it. Towed same trailer a few months ago and towed a flat bed with a 4runner on it and did not have this issue. I will try and get a scan tool and connect to truck with it.
 

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Discussion Starter · #5 ·
Don't know about the last time trans fluid/filter was changed. trans level is slightly over hot full mark with trans hot. Trans never got over 170 degrees either when the issue occurred. was always from 150-160 degrees
 

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ditch the cat, you don't need it and it creates heat, loss of usable power and so on. Find out it its tuned!!!!!!! get a quality EFI Live tuners tunes. If you have no idea who's tunes, or if any in the truck, then you need to have the piece of mind and assure yourself it is done right. This may or may not be a contributing factor in your issues as well.
 
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Discussion Starter · #7 ·
I will be ditching the cat and doing down pipe back straight piped. How do I find out if it is tuned?
 

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ditch the cat, you don't need it and it creates heat, loss of usable power and so on. Find out it its tuned!!!!!!! get a quality EFI Live tuners tunes. If you have no idea who's tunes, or if any in the truck, then you need to have the piece of mind and assure yourself it is done right. This may or may not be a contributing factor in your issues as well.
X2 on whats in red. Actually X2 on all of it. Talk to the guys at ATP, PPEI, or Duramax tuner about getting you set up with some good tunes. Not saying other tuners aren't fine, just letting you know a few of the big names to start with. You will not regret EFI live from any of them. If you're not sure what tuner is on it this would be the best route. Also you could have it flashed with a stock tune from the dealer, but in my experience with this they wanted way more than i was willing to pay lol. Anyway, everyone on here could go on for days about EFI live, Lets just get your codes if any first! :thumb
 
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I will be ditching the cat and doing down pipe back straight piped. How do I find out if it is tuned?
When you floor it does it smoke much? Mine when it was stock barely had a haze when i hammered it. Some tuners will smoke a pretty good bit depending on the power level they're set on.

Edit: When i say mine would haze, i mean it was visible at night when there were headlights behind me. Also mine had a 3 inch downpipe and 4 inch DP back exhaust when it did this.
 

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Discussion Starter · #10 ·
if I stand on it, sometimes I will get a greyish white smoke. but not a heavy smoke.
 

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Well its hard to say. I would say does it have a CEL but I deleted my EGR before my tuning just to experiment with it and mine did not throw a CEL. I did however have EGR codes stored but it didnt affect performance at all. So that being said its hard to say for sure if it has a tuner or not.. Maybe someone else can help more than me lol.
 

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Discussion Starter · #12 ·
Well I was able to get my hands on a scan tool today, plugged in and checked codes. said no codes stored. was unable to check trans codes. the scan tool I had was not that high tech. might be able to get a better scan tool tomorrow. but as of right now it did not throw any codes.
 
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