I checked the fuel purge system again - pulled the hose and plugged it and it made no difference in my idle surging.

I swear, this idle surge is so rhythmic, you could set your watch by it...mixture readings start out at 49% and gradually increase to the low 90's%, and then jumps back down to 49% and starts over...idle increases about 100 rpms during this - drops back then slowly increases 100 rpms, drops back and it all repeats.

When I disconnected the EHA, it steadily increased to 98.3% and stayed there...idle actually seemed smoother!

Which comes first - idle problems causing fluctuating mixture readings - or the other way around?

Anyone have any ideas?

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE