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Discussion Starter #1
Do any of you know if the ECM in these engines is detuned during the pre-defined break-in period? For example is the timing retarded until the ECM senses x number of miles, or engine hours and then automatically adjusts once you hit the predefined breakin limit? If so, do you know any specifics? I am just wondering if this engine is going to get better after I get past 500 miles, or whatever the number is.


Another question for a diesel newbie.... is it possible for a diesel engine to ping (like a gas engine does when you use cheap gas, or the timing is advanced too far) ? There are times in my LLY that I think I am hearing pinging, but like I said, this is my first diesel and I only have about 325 miles on her so far.
 

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Can't speak to the ECM programming, but can answer on "pinging." Diesels do not "ping" like a gas engine and the process is not as destructive as gas engine pinging. The distinctive "rock crusher" noise of a diesel engine is actually the detonation wavefront in the cylinder and a natural part of the diesel ignition system. The DMax has pilot injection in the Bosch system that pre-ignites and reduces the wavefront to greatly quiet the process. pilot injection cannot occur at high rpms as the injection cycle is too short for a double-pulse. Injection timing and fuel delivery can also produce some "rattle" at other times, usually associated with the engine load and timing at shift points. These are the "natural" diesel cycle noises that slip through the pilot injection programming and not a concern.
 

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Witsend,


Originally, my 2003 seemed low on power and my Dealer stated that the trucks have TQM torque contoll management, which basically allows the allison a chance to break in. After a certain mileage or number of hours the engine does run at full power. Have no idea if it true or not. My remedy was the juice.
Dave
 

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Discussion Starter #4
Idle_Chatter said:
Can't speak to the ECM programming, but can answer on "pinging." Diesels do not "ping" like a gas engine and the process is not as destructive as gas engine pinging. The distinctive "rock crusher" noise of a diesel engine is actually the detonation wavefront in the cylinder and a natural part of the diesel ignition system. The DMax has pilot injection in the Bosch system that pre-ignites and reduces the wavefront to greatly quiet the process. pilot injection cannot occur at high rpms as the injection cycle is too short for a double-pulse. Injection timing and fuel delivery can also produce some "rattle" at other times, usually associated with the engine load and timing at shift points. These are the "natural" diesel cycle noises that slip through the pilot injection programming and not a concern.

I am noticing a noise that sounds like "knocking" when I put the engine under load from accelleration. The noise goes away once I take my foot out of it and cruise at a steady speed. This doesn't sound healthy to me, but like I said in my original post, this is my first diesel, and maybe I will just need to learn to ignore it. The truck now has about 485 miles on it. Due to the low miles, I haven't towed with the truck yet, but I am concerned that if I am hearing this knocking now without a heavy load, that it will be constant once I have a 9000 lb trailer behind me. Is this normal noise for a diesel when under load, or do you think I have a problem?
 

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What RPM?
 

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WitsEnd said:
Idle_Chatter said:
Can't speak to the ECM programming, but can answer on "pinging." Diesels do not "ping" like a gas engine and the process is not as destructive as gas engine pinging. The distinctive "rock crusher" noise of a diesel engine is actually the detonation wavefront in the cylinder and a natural part of the diesel ignition system. The DMax has pilot injection in the Bosch system that pre-ignites and reduces the wavefront to greatly quiet the process. pilot injection cannot occur at high rpms as the injection cycle is too short for a double-pulse. Injection timing and fuel delivery can also produce some "rattle" at other times, usually associated with the engine load and timing at shift points. These are the "natural" diesel cycle noises that slip through the pilot injection programming and not a concern.

I am noticing a noise that sounds like "knocking" when I put the engine under load from accelleration. The noise goes away once I take my foot out of it and cruise at a steady speed. This doesn't sound healthy to me, but like I said in my original post, this is my first diesel, and maybe I will just need to learn to ignore it. The truck now has about 485 miles on it. Due to the low miles, I haven't towed with the truck yet, but I am concerned that if I am hearing this knocking now without a heavy load, that it will be constant once I have a 9000 lb trailer behind me. Is this normal noise for a diesel when under load, or do you think I have a problem?

Mine sounds just like you said. It does it under heavy accelleration.
 

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U can't believe the difference in 5-8,000 miles, since I've had 7 previous D/A when I get in the new ones they are real tight.


About the time I get rid of them they are starting to loosen up and run much better.


I think about 2000 miles things are starting to improve and it gets better from there.


I don't know about the noise u hear thou.
 

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Discussion Starter #8
Silveradogs said:
What RPM?

Around 2000 rpm. It may also be worth noting that I have swapped out the tires for BFG AT 285/75/16's, but I wouldn't think that would cause enough extra load to cause the noise I am hearing.
 

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I am noticing a noise that sounds like "knocking" when I put the engine under load from accelleration.  ......  This doesn't sound healthy to me,


 [/QUOTE]

Before Duramax, all diesels sounded to me like they were broken and ready to self destruct when they were running good. I heard a Duramax running next to me at a Qwik Stop and ordered mine the following week.
 

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Just got my first Diesel, 2500HD. I'm like a lot of the other guys, sure like the truck, but it's not as quite as thought it would be except at idle. Here the chattering noise anytime I'm on the throttle. It maybe that I'm so used to a quite gas engine that I need time to get used to it. Only have 180 miles on it. Plan on pulling a 31.5 Mountaineer this summer after I get it broke in. Just don't understand the word "quite"
 

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lawton said:
Just don't understand the word "quite"






I'm not sure if I can define that one, But I can define "Loud".


If you looked up "loud" in the dictionary you would find a picture of my Dads 91 Dodge Cummins.
 

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I wouldn't call my LLY quite quiet but its not cummins either
 

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Idle_Chatter was right when he said the diesel is not pinging like a gasser. What causes the ping in a gasser is too much spark advance which tries to push the piston down back wards. Gasoline burns progressively and the diesel fuel detonated before pilot injection. Essentially it made the diesel progressively burn. Mine turns the pilot injection off at 2400 rpm. I have noticed on occasion when towing that it was louder at 2000. Later! Frank
 
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