And then it started knockng and puked black smoke

[Bersaglieri]

Well I've had this truck about 20 days or so and yesterday, driving 25mph, it suddenly started to knock and puke black smoke. I pulled over about 200 yards later and trailered it home. It didn't seem to exhibit any warning signs that I noticed, however it's the first time we've had the truck down to 1/4 tank since we bought it. It's a 2002 CCSB LB7, 298,000 miles, and the truck is totally stock. There is no blow by or "puffing" out the oil cap and the second set of injectors were allegedly done about 32,000 miles ago.

This is not my truck, but this is pretty much what it's doing:
http://www.youtube.com/watch?v=mAhoMz7q-xk
and
http://www.youtube.com/watch?v=DiPrgaTdmzc


My logic tells me it's an injector stuck open. I've worked on alot of diesels over the years, however I'm relatively green with Duramax motors. Basically I'm here to ask what diagnostics I should perform to find the problem. A dealership buddy said to check the wiring harness, which I have visually, but with no luck. I found this in my searches on this site: http://www.dieselpowermag.com/tech/chevy/1304dp_going_the_distance_2005_chevy_silverado_2500hd/

I'm not much of an electronics guy, but I do have a multi-meter. If someone could break down a procedure on how to check the wiring harness and eliminate that variable first, I would greatly appreciate it.

I do have a PPE programmer, but it's off at PPE for an update. The dash isn't showing a SES light while running, but I'm not sure if they illuminate for all codes. At this point I'm thinking about jumping straight to EFI live for the sheer diagnostics, especially since this situation popped up.

 

[juddski88]

First, I would find a way to check the balance rates of the injectors. That should lead you to which one(s) are the biggest problem (rates will show a + or - 15 for a stuck injector. Does it have a dead pedal as well?

 

[Ed04zf6]

My 04 lb7 started doing the same thing. After chasing different things around I bot a v2 which allowed me to individually shut off each cylinder. I think a one of my injectors was stuck open. After replacing them it fixed the issue. I hope you get it figured out.

 

[baggedLB7]

You could take out the glow plugs and unplug the two big bail connectors on top of the motor and then crank it over and watch for fuel spraying out of the holes. That will tell you which ones are leaking or stuck open if they are.

 

[Bersaglieri]

Thanks for the replies guys. Is it true the PPE Hot+2 will not display balance rates? If that is true I'll buy EFI live V2 Monday morning and start diagnosing with that. ATP (Rob) seems to have a good V2 package.

I saw someone in an older thread mention the glow plug test for a open injector.

Not sure about dead pedal, I didn't drive it very far after the knocking started but it didn't feel dead to me.

 

[chevyburnout1]

Does it sound like this? This was my truck with a stuck open injector.

[YOUTUBE]dbkmKXjhU-U[/YOUTUBE]

 

[Bersaglieri]

That's my gal, she sounds just like that.

Is it safe to assume the injector is stuck open because of either mechanical failure or electrical ground? I suppose it could be a ficm problem commanding it open, but why would it suddenly get stuck open?

 

[chevyburnout1]

If it was electrical more than likely it would go into the fail safe mode of running on four cylinders. Can almost bet it's an injector.

 

[ripmf666]

Does it sound like this? This was my truck with a stuck open injector.

[YOUTUBE]dbkmKXjhU-U[/YOUTUBE]

Wish it would warm up here some. That and have time to tear into my truck more. After listening to your video then watching the under hood one I took I hear the sound better.
[YOUTUBE]zEbAKMQatYI[/YOUTUBE]
And another
[YOUTUBE]UnkOGaI4wEg[/YOUTUBE]

 

[S Phinney]

Use a V2 or Tech2 to turn off cylinders. It is most likely bad injector.

Sent from my XT1080 using Tapatalk

 

[Bersaglieri]

I did a resistance to ground check on the flat plugs going to each pair of injectors. So far it seems none of them [green wires] are grounding in the harness... so much for wishful thinking. Regardless, and because of time constraints, I'm biting the bullet and calling up IdahoRob. I knew it was going to happen sooner or later [Injectors and/or EFI live] I was just hoping it was going to be longer than a month from the initial purchase of the truck. Hopefully the EFIlive diagnostics can narrow it down quick cause I need this truck back in action.

Is there a EFIlive diagnostics manual or literature I could read up on while waiting for it to show up? Not looking to tune, just diagnostics.

Also what are you guys typically getting tune wise for a factory transmission truck? I'll probably just a 5 position switch.

 

[DAVe3283]

Mine did something similar while driving through Utah:
[YOUTUBE]rFFEocgPX_c[/YOUTUBE]

Turns out salt water had gotten into the bale connectors. Not enough that I could see any, but once I used electrical cleaner and let them dry out, everything was back to normal. I applied dielectric grease to the connectors, and it has been rock solid since (about 2 years).

 

[Bersaglieri]

What sort of diagnostics do you do to find the bale connector corrosion? Nevermind, saw the link in the video comments. Mine was the same deal, the injectors went from ZERO smoke to stuck open. Thing has run squeaky clean since I bought it. I'm really hoping it's electrical, just got to track it down. Since it's the first time I've had the truck down to 1/4 tank, I'm wondering if some dirt got sucked up...

Ordered some EFI Live today, that was a quick way to watch a cool G leave my wallet. it'll be here WED...

 

[juddski88]

How would dirt get into your tank? And then past your filter? We've cut up a few tanks from a variety of trucks and types of owners and still have yet to find any dirt..

 

[Bersaglieri]

Hey, I'm not ruling anything out, but with 300k miles in a desert environment, it's certainly a possibility. I've seen dirt/sand/whatever in tanks down here before. I'm not talking clumps but sometimes there is debris in there. Is it that unheard of for debris to cause a stuck injector?

 

[z71havinfun]

If it was electrical more than likely it would go into the fail safe mode of running on four cylinders. Can almost bet it's an injector.

X2 if it was electrical it would more then likely throw a fualt code
IMO its something simple stupid 99% of the time
you check all your boost tubes? boots? hole rubbed in intercooler? (usually upper drivers side if im not mistaken???)

 

[Bersaglieri]

I'm new to Duramax trucks but it don't see how a boost leak would cause idle smoke and a knock.

Do they produce codes for accidental grounds?

I'm really hoping it's something little, spending some more time working on it today. My diagnostic tools should be here tomorrow.

 

[DIESELMAFIAPER.LB7]

It's an injector no doubt in my mind I have had that same thing happen 3 times on different dmaxs

 

[MACKIN]

I'm new to Duramax trucks but it don't see how a boost leak would cause idle smoke and a knock.

Do they produce codes for accidental grounds?

I'm really hoping it's something little, spending some more time working on it today. My diagnostic tools should be here tomorrow.

At idle probably not as you suggest

 

[Dozerboy]

How would dirt get into your tank? And then past your filter? We've cut up a few tanks from a variety of trucks and types of owners and still have yet to find any dirt..

I had a bit of rust in mine when I dropped my tank to do the pick up. But it shouldn't get past the filter.