new duramax!

embs200

New member
Jan 1, 2012
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ATL, GA
Thanks for the reply and concern!!!

well has a miss/skip. black smoke on start up. drives with out smokeing then i hit a incline and it will pour hazy black smoke, then if i get on it, it will pour dark thick black smoke. skip always there, rough idol, Took it to a horrible shop and they said balance rates were erratic and random. +7 +8 being the highest they saw. I have icepicked all injectors and added dielectric grease. Guy I bought it from cut off # 2 injector and buttconnected a new connector(hmmmm). Put laser temp gun to exaust manifold and all ports read 120+ except for #2 which only reads 90.

throwing these codes p0461-- fuel level sensor circuit 2 out of range
p0670-- glow plug module control circuit
p2228-- baro sensor circuit low

here are the shops notes
cylinder balance test indicates erratic injector operation; random among injectors, no injector in particular.
Resistance reading of injectors in spec
1--.7
2--.9
3--.8
4--.8
5--.8
6--.9
7--.8
8--.8

There is no blow by and i dont suspect a leaking head gasket. Ordered a compression tester from harbor freight(couldnt hurt to test)

The truck is a 2005 lly with 225,000
gmc dealer said they replace injector 1 and 3 and needed additonal repairs but owner opted out of them. Also notice there is a high idol opiton on dash that i can turn on or off but nothing happens when i do.

Taking it to a popular diesel mechanic that is 5 minutes down the road who has a shop at his house he works out of. if i cant narrow it down to something by then hopefully he can tell me just dont wana have to pay for something i can figure out on my own. My good friend is a cummins mechanic and as soon as i find out the problem me and him will repair it.
Any ideas.. Thanks guys i really appreciate it

-Erik
 

embs200

New member
Jan 1, 2012
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ATL, GA
Guy i bought it from swears up and down that it needs an injector on drivers side but he couldn't remember which one. Claims he didnt want to put any money into it because he got it practicably free from a family member. So far everything he has told me including maintenance records and vehicle history has lined up with everything on carfax including the mileage the things where done at. Haven't caught him in a single lie and everything he said was wrong or that he already did has show to be truthful, haven found any surprises yet.
I wish the dealer would have put what additional repairs it needed in their notes, it would have saved me alot of trouble
 

JoshH

Daggum farm truck
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Feb 14, 2007
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Guy I bought it from cut off # 2 injector and buttconnected a new connector(hmmmm).

That's nothing new. The #2 injector connector is the most common I've seen have a problem. To fix it, GM sells a new connector pig tail with heat shrink butt connectors.
 

embs200

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Jan 1, 2012
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ATL, GA
that sound exactly like what he did. He told me that was the first thing he did when he had issues. But I didn't know if he did it right.
 

sweetdiesel

That's better
Aug 6, 2006
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Thailand
That's nothing new. The #2 injector connector is the most common I've seen have a problem. To fix it, GM sells a new connector pig tail with heat shrink butt connectors.

Josh

I've never seen this before? What year trucks?

I'm guessing lly since he did the ice pick thing
 

embs200

New member
Jan 1, 2012
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ATL, GA
could #2 injector be stuck closed and is returning all of its fuel causing crazy balance rates and dumping way too much fuel in other cylinders? Also has a terrible knock that is always there. Idk if its a "fuel knock " or even what could cause a fuel knock or "the knock im hearing" sounds like a gas motors piston slap or rod knock. But ive heard that bad injector problems can cause that knock. I just dont understand why im seeing alot of black smoke and no white smoke, and why all balance rates are off not just one.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,704
765
113
Texas!!!
Josh

I've never seen this before? What year trucks?

I'm guessing lly since he did the ice pick thing

Yes, It's a somewhat common problem on LLYs. Here are the part numbers.


This is the part number for the straight connector: 88988963

This is the part number for the 90 degree connector: 98017958

Supposedly the 90 degree connector is the only one you are supposed to use for #2 and #7, but I've put several straight ones on without a problem. I leave a little more slack in the wires so the tension doesn't side load the connector and cause future problems.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,704
765
113
Texas!!!
could #2 injector be stuck closed and is returning all of its fuel causing crazy balance rates and dumping way too much fuel in other cylinders? Also has a terrible knock that is always there. Idk if its a "fuel knock " or even what could cause a fuel knock or "the knock im hearing" sounds like a gas motors piston slap or rod knock. But ive heard that bad injector problems can cause that knock. I just dont understand why im seeing alot of black smoke and no white smoke, and why all balance rates are off not just one.

Do you have a check engine light on? Any scan tools at your disposal? It could be a rail pressure problem.
 

RKTMech

Idiot with a wrench
Aug 18, 2008
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The Norco's
Look by the Alt for wires rubbed thru on the sharp edge of the bracket, and find someone with a TECH2 to scan it.
 

embs200

New member
Jan 1, 2012
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ATL, GA
Ok i will find someone with tech2 and will check wires, does this sound like its electrical not mechanical?
 

embs200

New member
Jan 1, 2012
54
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ATL, GA
Im in georgia south of airport anyone know of the top of your head a good place, i thought about going to garmin but its a little far i want to drive the truck as little as possible.
 

embs200

New member
Jan 1, 2012
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ATL, GA
Checked alt wires, appears as if they have rubbed through in the past and the guy did somekind of splice to fix it. then raped it with some kind of tape.
maybe i should test it but it looks like he or whoever did a good job.