My truck started running horrible last week. It sounds like it has a dead cylinder but isn't throwing any misfire codes. Its smells like its running super rich at idle. If I rev it it blows wet black soot out of the tailpipe not just a little but enough to put a big black dot on my fence 5 foot away. My buddy seems to think I blew a head gasket. I haven't had a chance to run a compression test yet. Has anybody seen or heard of something like this?

 

Misfire code parameters are turned way up (or perhaps off) when you're tuned for a cam and/or converter. So you'll have to go about your misfire diagnostics a little bit differently. If you have EFI Live or HPT, or a decent scan-tool, you can moniter misfire counts while the engine is running. It will count misfires without setting the codes.

While you're at it, a compression test is never a bad thing to do. But it's probably (hopefully) okay.

 

Engine been using any oil all of the sudden?