ULSD hard part changes to the Duramax?

[Mark Rinker]

Can anyone point me to what componants of the DMax were modified to accomodate ULSD?

I am interested in what hard parts have been modified, and are backward compatible with LB7 and LLY versions of the DMax.

Injectors? Injection Pumps? i.e. If I get new new warranty injectors for an '02 or and '04 LB7, are they different than the injectors I originally got? How about an '05 LLY? '06?

[Duramaster]

The most obvious thing is the injectors in the LB7. They are their own kind. The next step is the LLY 2004 - 2005. And then when you get to the 2006 - 2007 LLY/ LBZ, those injectors look the same as the 2004 - 2005 LLY but they do not fit properly in the 2006 - 2007 LLY/ LBZ heads. Along with that, in 2006 the injectors had to be programmed into the PCM/ GPCM using flow rate programming. I am not sure on the injection pumps at this time. I know that the FRP has changed as well as the fuel pressures. Does this help?

[Mark Rinker]

Sure, it helps put the puzzle together.

So, replacement LB7 injectors installed today are the same as the ones that went in 2001-2004? Or are there upgraded LB7 injectors for ULSD use? :confused:

And what is flow rate programming, now that you brought it up? :)

[Duramaster]

What I am saying about the LB7 injectors is the last figure that I heard about 2 - 3 years ago? was that the LB7 injectors had been updated 14 times. And of course we know that the 2004 injectors have similar problems as the 2001 - 2004.

As far as flow rate programming goes......... in 2006 the General added another step to the injector replacement prodess. If you look at an injector from an '06 you will see two rows of numbers ( alphanumeric ). After replacing the injector you have to use the GM Tech 2 to program that alphanumeric code into the PCM.

Another thing about the ULSD is this.......... I asked the same question at GM Emerging issue seminar. They told me that the sulphur content in the fuel for fuel system lubrication is a mute point. Even when using "LSD" the sulphur content was not an issue. The fuel companies actually add "ADDITIVES" to the fuel for fuel system lubrication. They have evidently been doing this for years?..? So if that is the case, WHy do we push diesel fuel additives so much? :confused::);)