I use my 70's vintage analog dwell-RPM-voltage meter to check mine, using Pin 3 on the diagnostic socket, so your advanced technology should work.
If the older cars detect a fault, you get a constant percentage reading, and there is a table to decode it in the manual. If the reading is fluctuating, then you should see a change as you diddle the mixture. You should not have to turn it very far to see a change.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe