1. Check the dipstick. Oil should be clean and proper level. Might be overfilled, causing oil blow-by into the exhaust.
2. Look at hoses & connectors on or near the air filter housing. If something is loose or disconnected or not properly seated, it might cause the engine to run rough.
3. A loose/disconnected/damaged spark plug wire might explain explain the black smoke and rough running. But I can't imagine how this might've happen.
4. Injector cleaning? What did they do? Probably just added some injector cleaning fluid to the gas tank, which shouldn't cause any problems.
5. Give the dealer one more routine chance to make things right -- no need to yell (yet) -- including a properly-functioning CEL.
Probably a grunt did the original service and messed-up something.
2. Look at hoses & connectors on or near the air filter housing. If something is loose or disconnected or not properly seated, it might cause the engine to run rough.
3. A loose/disconnected/damaged spark plug wire might explain explain the black smoke and rough running. But I can't imagine how this might've happen.
4. Injector cleaning? What did they do? Probably just added some injector cleaning fluid to the gas tank, which shouldn't cause any problems.
5. Give the dealer one more routine chance to make things right -- no need to yell (yet) -- including a properly-functioning CEL.
Probably a grunt did the original service and messed-up something.
Im sure they didnt reflash the ecu, it probably had a CEL from running cleaner through it, they probably do what my shop does, run a cleaner through a vacuum line, most likely the brake booster line, into the intake which is actually more of a intake cleaner really but it is marketed as fuel injection cleaning. We have cars that will throw a CEL when its done and sometimes pop one up an hour or two later and we clear it and it stays off. Sounds like your problem was solved no harm no foul.