My Chevy 2500HD Diesel

[mazboy]

i need some input on the following.
I purchased a 2006 diesel and I pull a 3150 Montana.
Usually I can keep it at a steady speed going up hills/mountains but on occassion it seems like it loses power and then it jumps up 1000rpms (i assume it is downshifting?) and then it feels like my old gas 2500 going up.

is this normal?

thanks

[mcgiver2]

Mazboy are you pulling in the tow/haul mode.......because you should have enough power to maintaine a good speed

[PapaBeav]

Some time ago I had the same problem, and I thought it might be the fuel filter either having some water in it or being slightly restricted. So once I replaced the filter, the problem went away and it seemed to have more power. So you might try replacing it if you haven't done so recently. Or at least check to see if it has any water in it by draining it out the bottom. Speaking of filters, I think I need to replace mine again.

Rich

[HughM]

Rick is right on. With my Duramax if I'm getting close to 15,000 miles on the fuel filter I can tell a little loss of power. Anything over that and you run the risks of side of the road problems.
Hugh

[Delaine and Lindy]

I agree I would change the fuel filter, and I always had a spare filter in the tool box, you never know when you will get some bad fuel. GBY....

[mazboy]

thanks but the filter was changed and it still, on occasion, seems to lose the power.
i've never put it in tow mode because it had ran great. so, i'm at a loss of what's going on. nothing is showing up on the computer codes, been in 3 repair shops so far. oh wellll, life goes on.

[The Old Fogies]

I have a 05. I always us the tow mode, for two reasons. The tow mode changes the shift points and it helps when braking and downhill. Burns extra fuel, but I think that the wear & tear plus the safety.

[thor]

do you have a pieroameter? it measures the temp comimg from the turbo into the exhaust manifold.if the temp rises to high the truck will downshift to try to cool itself down and in the process it will loose some power.you can put a gauage to check and watch for this.also you should allways tow in haul mode.it changes the shift piont and stops your truck from lugging which incraeses engine temp .the gauge is calle a egt gauage which stands for exhaust engine temp.

[WorkerB]

Sandie,
When under load and not in tow mode you can get hard shifting. A great source for information on your Duramax is http://www.dieselplace.com . You can lurk around or join. It's free just create a user name and password and if you can't find a solution using the search function you can post your question. Very helpful folks over there. Hope this helps.
John

[Devildog]

what you mentioned for symptoms in the first post, is exactly what you would run into, if you were is hills (small or large) and not in tow-haul mode. The Allison tranny is expecting that you will nail the fuel to compensate for the loss of power in overdrive. Then finally it kicks down, and as you see, gains about 1000 rpm in the next lower gear to continue the pull.

I have always used tow-haul mode. Allison and engine are much more responsive, higher line pressures to reduce heat in the transmission, and then the braking feature. If you are on flat ground, or slight hills, once you go over 60 mph, it will kick down into overdrive unless you are stomping the go pedal. I usually maintain about 62 mph, and even on hills that have a little size, it will carry me over at 58 mph and not kick down to the next gear. I just feather the fuel. you're pulling about 14000 lbs, not much fuel savings, but I can average between 10 to 12.5 mpg with this method.
It is not your fuel or your filter. You've already changed that. Try tow-haul. Takes out the white knuckle. And remember, some of that loud roar you hear going up a hill, is the cooling fan keeping the engine cool.
Hope this helps. and the website for Dieselplace is fantastic. I've been a member there for almost 8 years.

[mazboy]

a little late but thanks to all. when i start pulling my 5th wheel again i will use the tow mode.
happy new year......