LB7: Proud owner of my first Duramax. But I am having problems with it.

Ericlb7

Eric
Mar 9, 2016
6
0
0
Ohio
I am brand new to the forum! Sorry if I am putting this on the wrong page! Long story short, Got tired of my 05 Dodge Cummins, sold it and bought an 03 ecsb lb7 with 150,000mi, and a manual transmission. I knew the truck fairly well before purchase. My new machine has a brand new tranny and transfer case, with added supports due to stress cracks on each. At same time a new south bend single stage clutch was installed. 9 months ago the cp3 pump went out of it and he had it replaced. It has a P.P.E. programmer installed on it also. I bought the truck 2 months ago and have had a few issues as of late. I drove it for 3 weeks with no issues. Then one day i drove to work parked for a bit and then fired it back up, drove about 3 blocks and it started running terrible, missing and total power loss. Never did completely staul out. I turned the truck off, started it again and didnt have any problems for probably 2 more weeks. I went to start my truck, battery acted dead. Popped hood, found loose battery terminal. Tightened it, started right up. The truck ran for 20 seconds and then started missing and popping and some white smoke. I shut it off for 10 seconds and then start it back up and it is good for 20 seconds and does the same thing again and again.I replaced the fuel filter, primed it, removed the air through that little bleeder, and it didnt change a thing. I think i succesfully removed all stored programs thinking i.should eliminate that... im no mechanic but i would like to try to figure this out and do it myself. Any advice on where to start would be great. Its not throwing any codes. Sorry it wasnt as advertised "long story short". Thank.you for any advise!
 

Burn Down

Hotrodder
Sep 14, 2008
7,092
28
48
Boise Idaho
Ah welcome to the world of the LB7:D... If it shelled a CP3 there is a good chance it sent some garbage into the fuel injectors, ruining them. You need to check the balance rates on the injectors.

Does the fuel filter head pump up nice and solid?

Welcome to DD.
 

Ericlb7

Eric
Mar 9, 2016
6
0
0
Ohio
The filter heAd does pump up nice and solid. I pumped it while running and made zero difference. I tried to check the tolerances of the injectors with my programmer but they were all over the place and I was really confused. my neighbor thinks he is a mechanic and is going to Check it out today, I'll report what he has to say. I just don't understand how it can run great for 15-30 seconds and then go to complete crap all at once if it is in fact the Injectors.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,775
2,043
113
Mid Michigan
Its not. Chances are its something else, but its impossible to diagnose these things from afar....
 

Ericlb7

Eric
Mar 9, 2016
6
0
0
Ohio
Well i thought maybe the glow plugs were pulling too much voltage so i unhooked them and made no difference. Now when i unhooked the connector for the glow plugs that also powers the intake air heater it made the engine miss and sputter instantly. The same thing it is doing after about 20 seconds with everything hooked up. Im not sure if this is all coincidence or not. I was able to beg the neighbor to hook up his scan tool and it showed the injectors all over place, but also showed the egr selanoid to be open the whole time. When it was shut off, when it was running, when it was missing, not sure if it is supposed to be on all the time. Can anyone varify? Thanks!
 

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
Start checking all your grounds. And have the batteries tested.

What kind of scanner is he using? Maybe he could log some data for us to look at? Or can you maybe take some videos of what's going on. Like Tom said it's pretty much impossible to figure this out flying blind.

Having no glow plugs or intake heater won't make the engine miss.

Sent from my SM-N910V using Tapatalk
 

Ericlb7

Eric
Mar 9, 2016
6
0
0
Ohio
He was using a snap on, wireless type deal... only reason i suspected the glow plugs was someone had mentioned that if they dont turn off it could be fooling the injectors to not push enough fuel into the cylinders because the temperature of the combustion chamber.