Rough Idle w/ black smoke

[aggieLR]

We drove 170 miles yesterday and everything was fine, but when I got home, my bumper was black on the corner right behind the exhaust pipe. This morning when I fired it up it was running rough and blowing quite a bit of black smoke when I reved it up. The truck is completely stock w/ 5000 miles on it. Any suggestions on what to check or possible problems?

 

[aggieLR]

This is a dark picture, kind of hard to tell, but this my an '04 w/ 5500 miles. The stripe I made w/ my finger, but the rest is dark colored. Anyone else's 3rd gen. do this? It didn't look like that when I left for the trip.



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[Vaughn MacKenzie]

Aggie did it blow black smoke when you jabbed the throttle or did it smoke at idle? The amount of soot on your bumper doesn't look excessive, mine gets like that after a few days and I'm running stock fueling. Have you checked your air filter yet? 5500 miles isn't a bad time to look, mine was toast by 10K miles.



The rough running doesn't sound normal though.



Vaughn

 

[aggieLR]

It only smokes when I rev it up. I wasn't sure about the bumper though, because I hadn't seen it before this trip. The air filter is a little dirty, but not excessively. I'm gonna change the air and fuel filter tommorow and see if it helps. It only idled rough this morning. I shut it down and started it back up, and it was still doing it. But after I drove it for a few min. it quit.

 

[Vaughn MacKenzie]

The reason I asked about smoking at idle is because at 10K miles mine started doing that, smoking bad at idle and all RPM & load ranges. Even with new air & fuel filters. I had at least 10 times that much soot caked on my bumper when that happened. I could scrape teaspoonfulls of soot from my tailpipe! The weird thing was my truck ran great, MPG & power was normal and my oil stayed clean.



After 2 trips to the dealer they replaced the ECM and the smoke went away, been great the last 20K miles.

 

[WyattEarp]

Im no expert on this but on my 2000 I could always tell when my fuel filter would start to get dirty at idle and flat roads if you can find any here(few and far in between) it ran fine but going up hill it was sluggish and felt like it was holding back, changed the filter and no more sluggish feeling. Maybe its a dirty injector that may be a far fetched idea with that low of mileage...

Just thought i would chime in, Im always looking at the forums for future reference if ya know what i mean.

 

[rbattelle]

Black smoke indicates incomplete burning. It makes sense that it would be most pronounced at a cold idle, but that still doesn't mean it's normal, especially combined with a rough idle. I would suspect something in the fuel system - either injectors, filter, or ECM as Vaughn mentioned.

 

[ScottBrown]

Your exhaust pipe is on backwards I have changed my muff so I angled the tailpipe down a little, kept the soot off the rear bumper. Listen to that Vaughn guy and others, good points

 

[claymike]

I don't get the black smoke but after towing my 5er my bumper looks just like the pics.

 

[Vaughn MacKenzie]

Originally posted by ScottBrown

Listen to that Vaughn guy and others, good points

I heard you need to watch out for him though :-laf