Prostate exam for cars

I have always felt you could learn a lot about a car by sticking a finger in the tailpipe. My car’s tailpipe has always been clean, but suddenly I noticed a bit of noisy engine idle. A finger in the pipe showed black (carbon?) deposits.

What does this mean, and is there an easy fix?

And a “putt, putt, putt” would indicate …what? The engine is running overly rich. If the check engine light is on, have it scanned (free) at many auto parts stores. A dirty air filter, poor spark plugs and wires, erroneous coolant temperature indication to the engine computer, and a few other things will cause a rich condition. The tail pipe? Mechanics have found that what comes out the tail pipe is as important as what goes in in the intake, for years and years.

It means you’re placing entirely too much emphasis on your tailpipe as a diagnostic tool.
It also means you’re placing entirely too much confidence in our clairvoyant abilities. You haven’t told us anything at all sbout the car, the noise, or anything else relevant.

Make, model, year, mileage, maintenance history, what conditions does the noise happen under, what affects the noise, is it in synch with the engine or the car’s speed?