All you need to set the duty cycle properly is a meter that reads duty cycle, or an oscilloscope that is capable of long time base. You set it for 50% on/off ratio.

Odd that you had to richen the mixture. Usually the previous owner richens up the mix in order to compensate for a vacuum leak they never bothered to fix.

You may wish to verify that you aren't in fact doing just that, or that you aren't just slowly losing your O2 sensor.

__________________
-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition