LB7 Injector problem - Diesel Bombers

Chevy/GMC Duramax 01-04 LB7 Discussion of Chevy and GMC Trucks with LB7 Duramax Turbo Diesel Engines

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Old 04-17-2012, 12:21 PM
Diesel Fan
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Join Date: Apr 2012
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Default LB7 Injector problem

So I talked to one of San Diego's best Diesel shops and found out some interesting info. It seems the LB7 injector problem is not the actual injectors. It's in the programming of the truck's computer. He explained it to me saying that the programming is firing the injectors about 15 degrees before TDC. He said something about them firing 5 times every time at idle per cycle. Don't quote me on that part because I didn't fully understand what he was talking about. This came up because I told him that I had replaced my injectors when they went bad for the third time with Industrial Injection's 50HP injectors. He asked is they reprogrammed the computer and I looked at him with a blank stare. He laughed and said that I have not fixed the injector problem. He suggested EFI Live tuning and to get rid of my Edge and Hypertech programmers. He doesn't sell or do the EFI tuning so he has nothing to gain by telling me this which leads me to believe everything he is saying.

Has anyone else heard of this?

Thanks to all who read and answer!
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Old 04-17-2012, 09:18 PM
Diesel Enthusiast
Join Date: Apr 2012
Location: Central Illinois
Posts: 113

Get rid of both the canned tuners, only cause problems.
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Old 04-18-2012, 01:57 AM
Diesel Bomber
Join Date: Dec 2010
Location: Fool's Golden State
Posts: 1,187

LB7 only uses two pulses per a power stroke. pilot and main. i think the later years that have the piezo injectors have up to five injections. as the engine progressed through the years the injector problems became less yet the number of injection cycles increased.

so it is not the number of cycles that does it

check this link out: Duramax Fuel Filter, Duramax Diesel Fuel Filter, Duramax Fuel Filter Change

it may or may not be true but another side of the story

some of those "canned" tuners will raise the rail pressure which it has been blamed on too. by the way, most EFI Live tunes dont turn off any of the injection cycles.

the problems with the injectors probably lies somewhere between injector design and fuel issues. not programming
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Old 04-18-2012, 03:53 PM
Diesel Fan
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Join Date: Apr 2012
Posts: 19

I read that article and I gotta say, that's a very well written article and it appears that he definitely did a ton of research. It really sounds like the main culprit is the filtration system. I have a FASS system on mine and the last time I changed the filters I cut open the additional 2 micron filter and it was completely black. There was a lot of rust on the inside on the metal screen and at the top where the gasket is. This all adds up and that article backs up what I saw. Thank you for the link!

I have the truck in the shop as I mentioned before and they just did a test and have determined that my head gaskets are gone. I feel that my injectors are new enough that I'm hopeful that they haven't been damaged too much from the possible water intrusion that was evident during the last filter change.

Will repost when the work is completely done and I get some more definitive answers. I'll be throwing in the ARP head studs this round too btw.
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