Chevy/GMC Duramax 06-07 LBZ Discussion of Chevy and GMC Trucks with LBZ Duramax Turbo Diesel Engines

2005 Duramax wont go over 2000 RPM

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Old 11-21-2012, 06:14 AM
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mad 2005 Duramax wont go over 2000 RPM

For more than 2 years periodically out of the blue the engine will not rev over 2000RPM! if you stop and turn the truck off and wait 2 minutes and restart it will go back to running fine, sometimes for a minute sometimes for a month. i took it to a dealer and they said it was the computer, egr, and egr cooler. I replaced them all and it made no difference. i have put over 50k miles on the truck fighting this , any Ideas? The truck has 215k and runs like new when this is not happening.
 
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Old 11-22-2012, 01:55 AM
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The truck is obviously is limp home mode. How old is the fuel filter? Is there a pattern to this like hard aceleration then limp or cold mornings, etc. Any codes?
 
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Old 11-22-2012, 08:32 AM
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I have changed the fuel filter multiple times. I will take off from a stop and upon acceleration it will stumble and then boom it just won't go over 2000rpm. This does not generate any codes either!! So anyone have any ideas??
 
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Old 11-22-2012, 03:35 PM
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Throttle sensor?

I believe anything that will put the truck into limp mode will generate a code. So with out any codes this one could be hard to figure out
 
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Old 12-02-2012, 09:39 PM
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This happend to my brothers 01 LB7. He would be driving around normal nothing wrong. But as soon as he hit the pretty steep hill by our house and he would need to get on it, by the time the truck would hit 2nd or 3rd gear and hit 2000 rpm, it would startle really hard, a check engine light would come on, and he couldnt go above 2000. If he was real easy on it he could shift without going above 2000. But the problem stopped when he replaced the injectors when one finnaly stuck open at 160,000. But either way, the chevy dealer mechanic said its either injectors, fuel filter, or map sensor on your air intake.
 
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Old 12-04-2012, 06:08 PM
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My 2003 did this aswell, it was because of a faulty CP3....

didn't throw any codes but a local diesel shop offered to replace my pump pro-bono if this was not the problem...

turned out it was the problem and my truck was fine after this...

i first became aware of the problem when i ran out of fuel, i would start up the truck and it would not rev over 2000rpm...

is it like the rev-limiter was moved to 2000rpm or does it pop and smoke??

because mine acted like the rev-limit was lowered to 2k RPM
 
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Old 12-04-2012, 06:20 PM
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Originally Posted by angelic0- View Post
My 2003 did this aswell, it was because of a faulty CP3....

didn't throw any codes but a local diesel shop offered to replace my pump pro-bono if this was not the problem...

turned out it was the problem and my truck was fine after this...

i first became aware of the problem when i ran out of fuel, i would start up the truck and it would not rev over 2000rpm...

is it like the rev-limiter was moved to 2000rpm or does it pop and smoke??

because mine acted like the rev-limit was lowered to 2k RPM
this will occur from low rail pressure, which happens to have it's own code. should have turned on the CEL. odd that it didn't
 
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Old 12-05-2012, 09:37 PM
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hmm, maybe my rail sensor was faulty ?

never triggered a code, but they changed my pump and it went away.... at least for the time i owned it afterwards... like 3 months or so...
 
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Old 03-22-2014, 03:14 PM
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shim your fuel rail fitting. It is probably popping open and putting it in limp mode
 
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Old 07-18-2014, 07:49 AM
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I have an 07 duramax usually towing about 10 to 20k on average, it has 271k miles. It recently went into limp mode while towing a dully on a flat bed. Three codes came up one was #8 glow plug, fuel rail pressure low, and temperature too low on coolant any advice is greatly appreciated
 

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