But I suspect that something else is going on here. IIRC, the OVP powers the lambda controller and the idle relay. If the mixture is properly adjusted and the warm-up regulator is working, all that the lambda system does is fine-tune the mixture. It sounds like, in your case, that the basic mix may be lean and the car needs enrichment from the lambda system to run, or that it's not getting enrichment from the WUR.

Recommend that you check your on/off ratio and control pressure, and make sure that both sides of the WUR are holding vacuum.

__________________
Chuck Taylor
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