Rough running, black soot in the exhaust...

[djratlif]

First off, I have been loaning my beloved pathfinder to my brother for a few months as his car has been down and no cash to fix it. I got a call yesterday and he told me it was running like crap, and sounded like a Harley when he tried to move it. It has been having issues for a few months with a rough start and idle until it warmed up, after which it ran fine and all was well. Now it is doing the same stumble as before, but not clearing up after a few minutes. This is accompanied by a lot of soot pouring out of the tailpipe with some heavy smoke. I can't smell coolant, and when I checked the radiator the coolant was not showing contamination.

I am thinking maybe something is wrong with a valve seal and guide somewhere, but didn't think it was a common problem for these. The truck has over 215K miles though, and has had a rough past before me from what I can tell. Does this sound like a feasible problem or has anyone got any other places for me to check? I haven't had time to check compression yet to see if there is a problem for sure with the engine.

Any help is appreciated, Derek

 

[Slartibartfast]

Sounds like a bad coolant temp sensor to me, the truck thinks it's negative Hoth outside so it richens the mix to where it barely runs. Any codes?

[djratlif]

no codes right now that I know of, the dash is kinda screwy though anyway so the light probably won't turn on anyway. I haven't checked any of the sensors yet but that will be added to the list now.

[Precise1]

Check the ECU for codes, don't look at the dash.

It could be the coolant temp sensor, a failed injector(s), the O2 sensor and a few less likely things. Use the diagnostics first...

 

B