muffler?

[Brian Cembor]

Well, I replaced the O2 sensor last month, since I have owned the car I have
not checked the plugs or the ignition. Should I check to see if the plugs
are fouled at all?
I don't think there is a vacuum leak as power appears to be fine and engine
runs smooth, no stumbles.
Now, I did read about the ECU ground and do know that mine has not been
moved, or am I think of the MAF? Should I ground the MAF it hasn't been
done?
And how to check for faulty ignition? I don't have any CE light coming up..

Brian
No, your ECU has learned the correct settings by now.
The main causes of a sooty exhaust would be:
- Bad O2 sensor
- Bad ECU ground
- Vacuum leak
- Faulty ignition