I've had the car for about 4 years, and no, I have not changed the oxygen sensor. when should it be changed?
ANS: only when the Lamda tester says it's broke!

also, i put my finger up the exhaust to see if there was substantial soot in it, and there wasn't. does that mean its not TOO rich?
ANS: NO!

Again, guys, I'm looking for some non-techy ways of detecting an abnormally rich mixture, because the fuel consumption is not THAT high - its 18-19 mpg, as compared to 22-23 mpg earlier.
ANS: There is no NON-TECHY way to determine proper mixture! Your dealing with a car not a dog! Touchy-feely doesn't work with a car!

Also, what does the fuel-air mixture screw adjust? someone told me its meaningless to adjust it, since the computer will turn it right back. Then why does it exist at all?
ANS: Give it a few turns and then watch the fun! Don't touch it without a Lambda tester AND know what to do!

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Regards . . . . JimF
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'94 S500 Cpe

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