2005 Duramax pouring out black smoke sometimes ?

[jd720]

My Duramax with 170,000 miles recently started pouring out black smoke intermittently. Yesterday I was going down the road at about 65 or so and it started smoking like a freight train for about 4-5 miles then just cleared up and was fine.  I noticed when this happens it looses some power , the engine gets louder and the temperature goes up to 210 from the 190 then when the smoke stops it goes back down to  190 which is where it normally runs. I bought this truck new and the only modifications are a Predator set at 65 hp over and a cold air intake which have both been on it 18 years. I changed the fuel filter and added some diesel kleen but it still does it. The check engine light never comes on so I doubt there are any codes stored. Anyone have any idea what the problem is ? 

[64BAwagon]

My LLY would do this when the turbo vane sensor went bad. 

Did the service engine light come on ? if so what codes. 

Lots of things could be causing it. 

[jd720]

No check engine light that`s what is so aggravating to me. If the check engine light would come on I could just get the code and get it fixed. There are several possible problems I just don`t want to just start throwing parts at the wall and hope something sticks. Thanks

[64BAwagon]

Thats odd, you would think it would have a code. Did you check it just to be sure ? 

You may have gotten some bad fuel, had that happen before, down on power and ran rough but no code. 

Depending on where youre at I would think about throwing a half bottle of Power service 911 in it and run the fuel down. 

 

[CamGTP]

Kinda sounds like a leaking injector with the black smoke.

 

More fuel in the cylinder can make it like a fire hose is a sense, more fuel can increase EGT's and increase coolant temps.

[jd720]

Not sure about an injector. The truck runs just like new till it does this then goes right back to running like new so something is changing  or not doing what it should. I drove it 2 days about 32 miles each day and it was fine but the next time I drove it this happened twice so I really can`t  trust it till it`s fixed .

[davester]

CEL may not necessarily come on, it only comes on for some codes.  Hook up a code reader and check for codes.

[jd720]

Ok I`ll try that tomorrow. I thought it would always come on if there was a code stored, Thanks

[jd720]

Ok I had it checked and the only code stored is P0700 transmission control module. This makes no sense to me because it shifts just fine. 

[CamGTP]

P0700 is generic code, a higher end scan tool is required to read the TCM and see what is the cause for the transmission code.

 

The black smoke wouldn't be a transmission related code though. It's going to be fuel related or "ignition" related. Black smoke is unburnt fuel coming out the exhaust. Injector failures are fairly common on the older Duramax engines.

Edited January 30, 2023 by CamGTP

[64BAwagon]

If it does have a bad injector you should be able to see it if you can get the balance rates. I ran a scangage 2 on mine and always knew what was going on. At least 2 times it helped me to limp the truck home. I had the ability to scan and clear codes.  

 

[jd720]

Ok I took it to local shop and they plugged it in and apparently it was the EGR valve so I had them replace it and so far it hasn`t done this again. Hopefully it`s fixed but time will tell.