Refer back to my response to Viper8315:How did it perform BEFORE you started doing modifications?….
When it's at 65mph and refusing to accelerate, what gear is it in? If it's refusing to downshift then it may not be an engine power problem. You could try running manual mode to force a downshift. I know that's not a long term solution but if forcing the "correct" gear gets you the commanded power then at least we've narrowed the problem down a bit.Stock tires on this were 34.2 (275/65r20) and it now has 35’s. Some increase, but very little change.
Great idea, I’ll give that a try.Had a friends truck a few years back that had a similar problem, turned out the throttle wasn't opening to FULL throttle adjusted it and made a big difference felt like a different truck.
Never heard of this! Sweet. I need to look into this for sure, not sure how to adjust that or check. But I’ll do some digging.Had a friends truck a few years back that had a similar problem, turned out the throttle wasn't opening to FULL throttle adjusted it and made a big difference felt like a different truck.
Next time I hook up the trailer I’ll be able to get exact EGT’s off the idash and post when I do 👍🏼These trucks have a lot of safeguards built in to prevent damage to the driveline and motor, and I'm willing to bet that since the truck has no issues while you're on flat ground, 65mph or so on an incline is where the truck is able to settle at an EGT that it feels is safe. The ECM and the Derringer both will back off the fueling rate if the EGT's are getting too high for comfort.
Since you have the Derringer do you also have the iDash? I'd be interested to see what your EGT's are doing in the situations you're describing.
Also, 80 mph is pretty fast for towing 10k lbs. Make sure the tires on your trailer are rated for that speed, or you might be setting yourself up for a bad time.
Yeah the gearing was a discussion I had with my mechanic/dealership when I bought the truck. All these 10 speeds came with 1 gear ratio option for the duramax engine. Would have elected for the lower of the two if I had the choice.Almost sounds like you don’t have the right gearing for towing. I would check your vin and see if you can come up with what ratio your rear end is
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Yeah I wasn’t planning on adding anything to it. This is my 4th duramax so I know what these trucks are capable of, wasn’t impressed few months after I bought it when I hooked the trailer up (hence the mods). I’ll go back to the drawing boardI would put it back to stone stock, especially if it goes to dealer!! Change the fuel filter and possibly air filter but use all OEM parts , JMHO but Never never never use aftermarket anything except cosmetics. My 19 is different but when it was new it would pull a hill at speed with the cruise but was a dog with me driving it, it got much better when it got to around 15,000 or more. Good luck with it ,it should pull any hill at 65 + but also altitude and air density are a factor but it should never be a weak dog!!