Oh yea, I forgot the switchover valve. I just plugged it with a short piece of hose with a machine screw in the end.

I'm expecting to get a CEL, but I think it takes two or three occurances of the ECU demading pump run without the corresponding response of the O2 sensor. I'm a bit of an electronics hack, I suppose it should be possible to fake the ECU into thinking the pump is running by altering the O2 sensor voltage. I know some of the hotrodders have developed O2 signal generators for just these purposes. The voltage supplied to the magnetic clutch coil when the ECU demands pump on could probably serve as a trigger for the the fake voltage signal........I might try to rig something up.

By the way, my musings here are about how to do this, not whether or not we should.................

J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles