Help leaving this afternoon on an 800 mile trip. Completely stock 05 2500 d/a with 7500 miles
For last 2 weeks I have had intermitten heavy black smoke while cruising at freeway speeds light throttle. It happen about 4 times each and lasted for maybe a mile then would clear up. There was no loss of performance at any time. I changed the Fuel filter (had approx 5k miles on old one). And did not note a problem until yesterday when it started happening again only this time I could hear a distinct ping like in a gasser with cheap gas. I let off the throttle and then and smoke was gone. I applied light throttle and this time the pinging and smoke were back only worse cars behind me were giving me alot of room. The the pinging started getting quicker and louder then a very loud ping followed by blue smoke and then all is good again. I drove straight to the nearest dealer, their diagnose was " no codes and can't duplicate the compliant. I reminded them of the long trip this week and just repeated themselves.
What would happen if I take the truck on the long trip if the pinging comes back will it harm the motor?

That is too weird the dealer said "no codes". There's a lot of sharp folks on the forum, hopefully someone will give some insight soon!

My 2005 did the exact same as yours at around 13000 miles. I took it to the dealer and there were no codes and they couldn't duplicate.They then said that my computer needed to updated. They did the work and now it is two weeks later and it is in the shop again. They now claim that #1,3,7 injectors are shot and need to be replaced. At first they tried to blame the injectors on bad fuel. After I told them they were full of #$%@, they replaced them under warranty. I pick it up in the morning, and will update forum with exact work performed.

i would say injectors on the way out..that is the same symptoms that our company truck had

I would agree on the injectors.

Possibly a wiring harness.

We had one come in last week with similar problem and it was the wiring harness.

I had the similar problem with my truck. Heavy black smoke, pinging, but I noticed a loss of power. No codes found but the mechanic pulled out the EGR and it was clogged with carbon. Replaced it and he suggested I change where we get our fuel. Not one problem ever since and that was four months ago. This may be a starting point, good luck!

LT

LT Construction Company.

2004 Silverado
D/A
LT--Ext Cab
All Stock

intermttent sticking injector add a good fuel additive dealer was told to do so on all new trucks. my old avm said this had to be done prior to replacing any injectors. standadyne make additive as well as bg petro spec and many otherstry this should help for now.

Thanks for the suggestions I will try the fuel additive first.
I just got back from my trip truck ran fine the only smoke was during heavy acceleration and there was not as much smoke as before. But until the problem started I never saw smoke, so I am sure the problem is/ will get worse before the dealer can fix FYI average speed was 75MPH at 14mpg does that sound about right? Normal around town driving is 15-16mpg for me

Milage right on for 75 mph... Have read other threads where the early '05s had the same symptoms you described. The end result was a "reflash". I'm sure someone will point you in the right direction with a link... I can't find where I read it.

I am having the same problem with the pinging and the heavy smoke. It started to do it after I would get off the gas and let the truck coast, like downhill around 70mph then when I would get back into the throttle it would start pinging and just spew all kinds of smoke. I thought I blew the motor or something. Now it is doing it more often like when I am sitting at a stop light and accelerate all kinds of smoke and noise!!! I thought it was the performance computer that I had in the truck but I disconnected it and still it does the same thing. Also the check engine light didn't come on either.. I think it's got a bad injector. but not sure. My last duramax (2001) when the injectors went on that there was no smoke!
If anyone knows what the problem is please let me know..

leaking injector into cylinders

leaking injector into cylinders

That's not possible on the LLY's only on LB7's.

I had the same problem on my new dmax at 2500 miles. The pinging and black smoke was caused by a loose hose going to the turbo charger. Fixed by a Chevy dealer in jacksonville Tenn.. 8500 miles now, no problems.

That's not possible on the LLY's only on LB7's.

of course it is possible. what is not possible on the lly is for it to leaak into the crank case. hav seen and replaced injectors on an lly for leaking into the cylinder. it leaks fron the nozzle it selfright by the pintle.

I have the same problem and I am going to try the additive first. I believe in the back of my mind it is a sticking injector.

I wrote about this same problem a few weeks ago, It started with the black smoke at freeway speeds for a mile or two and then would stop. then after a while it stated to ping a little, and a little more everytime that it smoked. The last time that it did it to me was when it started to knock or ping really bad and smoked black and blue/grey. I pulled over and put a gal. of fuel additive in it and it went away untill today. my truck only has 5000 miles on it. this was about 800 miles ago. The dealer never found anything wrong with it. so they say!

Check your intercooler boots. We had one in the shop a few weeks back and it had the same problem and we found the Intercooler boots were loose and 1 was half way popped off. Just a thought.