Today i went outside and flushed my radiator then started my truck up to burp the lines. Well like usual latley my truck has been running rough at the start and struggles to stay running (Never dies though). I just replaced my spark plugs and that got rid of my Random Misfire code, but its still idiling rough and when im driving and i let off the gas the RPMs plumment to five hundered then back to 900 or a thousand like they are supposed to be. Well while i was trying to burp the lines the truck was at a idle barley running then it died, started right back up with out to much trouble just for it to die again, so on the next start i gave it some gas and reved up only to see a faint cloud of smoke and black marks on the ground under were my pipes come out of the back of my truck. It dosent smell like oil or fuel really, if anyone has any ideas as to what kind of problem i have id love some input.

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You blew the soot out of it...lol. Not sure where it comes from though. Catylitic (sp) converter?

 

I was thinking the same about the cat being clogged and it blew it out.

 

Hmmm just got the cod P0171 and read on another site that he was having the same problem(terrible gas mileage and had black stuff being left on the ground, but sadly he never got an answer

 

Yea I would say it's just some built up carbon in the exhaust somewhere. Some SeaFoam should help that issue I would say

 

You might want to consider the CC being the source of your trouble with that black soot and with how it is running rough and all.

 

What is CC?

 

catalytic converter

 

Wow i wasn thinking lol

 

Lol yeah you see so many acronyms and abbreviations on here, sometimes easy to do.