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I just picked up my new Duramax C.C. 4x4 last week it is my first diesel and I love it! The towing power is awesome nothing like a gasser.As soon as Edge comes out with the juice for the LLY I will have it
just one question for you guys ? why does it accelerate a lot faster at 3/4 throttle than at full throttle?
 

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Another good question I thought was crazy to ask! Mine does the same thing! Anything past 3/4 really does not seem to do anything but make noise. Sometimes I floor it, and I think where is the power? (almost got rear ended passing the other day), then sometimes at 3/4 or 1/2 throttle I think holy s__t this thing rocks!? Wierd, hope the juice when available fixes this and the turbo lag!!
 

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Your feeling horsepower above 3/4 throttle. At around 1/2-3/4 you have a lot of torque working for you, that is why you feel like you stop when you get up in the rpms.
 

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this is just a guess but.....diesel's build speed through torque mostly. When you have the engine reved near it's readline it's out of it's "curve" so to speak. Although you have 310 h.p. on that LLY that nowhere near provides the push our butt sensors so love to feel. When you're going 1/2 to 3/4 throttle you still have the engine in it's 2000-2300 sweet spot which is where mine really builds momentum. And if I'm way off on this I'm sure someone who really knows will chime in.





MarkEdited by: DURAMAXED03
 

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My 2001 was that way. I think it's computer controlled torque management. It won't allow the truck to hurt itself.
 

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I've owned two powerstrokes and now the Duramax, all three trucks performed better at 3/4 throttle versus full. I have wondered why they performed like this also. But I have learned not to floor the pedal to achieve maximum acceleration.


Corsair
 

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I'v notist this also on my LLY, anything past 3/4 just makes noise. But on my last truck a 2001 LB7 full throttle acceleration worked great with lots of pull you back in the seat power. Does anyone else think this is odd.
 

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I think that it has a lot to do with the fact that you are not mechanicly linked to the throttle but rather by an electronic accelerator. At times even though your foot is not all the way to the floor the electronics are giving nearly full throttle. I would like to hear a Tech. answer this one.
 

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A tech might be the solution to this question, but IIRC, I read somewhere that the LLY (and maybe the LB7) does not allow full power from a standing start or even in the first gear on the Ally, in order to protect the drive train.


My firetruck has a 500HP Series 60 Detroit in it with a big Allison behind it, and it's limited by the computer from a standstill to protect the drive train.


Any reason to believe this might not be the case here? I think Hoot mentioned something about this possibility as well....
 

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I read somewere, not sure where that the LLY is limited to only 300hp in 1st and 5th and 310 through the rest of the gears to prevent slipping in the allison. im not sure about the six speed manual though. But I do know that this is a fact.
 

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The LLY is de-rated to the LB7 power levels when you put the manual trans behind it. That's per GM's web site with engine info.


Anybody know if there is a further computer controlled power restriction at low speed or from a stop in 1st gear on the Ally?
 

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Doesn't make any difference if I have full throttle. Anything over 1/2 and the tires break loose. Later! Frank
 

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I've also read that the LLY is detuned to 300 hp 520 ft lbs of torque in 1st and 5th gear so it doesn't hurt anything. I read it on another forum that exsplained all the upgrades to the LLY.
 

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My 2004 c4500 w 6.6 and 6 speed is limited to 2100 rims. Any suggestions?
First welcome to DP.
Never had good luck highjacking another thread not inless it's very simular to your symtoms.
Should of started your own.
I just picked up my new Duramax C.C. 4x4 last week it is my first diesel and I love it! The towing power is awesome nothing like a gasser.As soon as Edge comes out with the juice for the LLY I will have it just one question for you guys ? why does it accelerate a lot faster at 3/4 throttle than at full throttle?
So what's the similarity with this thread your having?

Your not giving us not much to work on. The more detailed the better.

You have a CEL on?
Any codes?
When does it go into limp mode?
Any aftermarket goodies?

You have a fuel, or engine limp.

What is Limp Mode?
There are mainly two limp modes that the Duramax performance crowd may experience…fuel and transmission limp. The way to tell the difference without checking codes is a fuel, or engine limp, will limit rpm to usually 2000rpms allowing shifting, and a transmission limp will limit shifting without limiting rpm. Transmission limp will usually give a bang/jolt and be stuck in one gear. This is a fail safe mode. Usually pulling over and turning the truck off and cycling the key a few times will take it out of limp mode and you will be back on the road.

Did I say post your codes.
 
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