thank you mb doc, it makes sense to me now. diverter is brand new, O2 sensor is less than a year I think, smog pump is maybe 2 or 3 years old. here is my list off repairs and routine jobs: **Mercedes-Benz**
*Belt replaced 10/23/10
*Air pump diverter valve replaced 10/23/10
*Oil Pennzoil 20-50 changed @ 265,730 9/16/10
*Oil filer Bosch replaced @ 265730 on 9/16/10
*Water pump replaced 7/24/10
*Thermostat replaced 7/24/10
*Belt tensioner replaced 7/24/10
*Belt shock replaced 7/24/10
*Coolant replaced Zerex G-05 7/24/10
*Radiator flushed 7/24/10
* Oil cap gasket replaced 7/24/10
*Belt replaced 7/24/10
*Coolant tank sensor replaced 7/24/10
*Coolant bypass hose replaced 7/24/10
*Radiator expansion tank replaced 7/23/10
*Radiator cap replaced 7/23/10
*Overload Protection Relay replaced 7/9/10
*Transmission fluid changed 7/3/10
*A/c evacuated and recharged with R134a 6/10/10
*A/c cut off switch replaced 6/9/10
*A/c temperature sensor replaced 6/9/10
*Auxillary fan switch replaced 6/9/10
*Air temperature sensor replaced 6/9/10
*Transmission pan gasket replaced 6/7/10
*Air filter changed on 5/22/10
*Transmission filter changed on 5/22/10
*Transmission fluid changed on 5/22/10
*Distributor cap changed on 5/22/10
*Distributor rotor changed on 5/22/10
*Fuel filter changed on 5/22/10
*Oil filter- Bosch Premium part number (3421). Done on 3/13/10 @ 254747 *Oil
GTX 20-50W 5.5 qts done on 3/13/10 @ 254747.

*Oil filter- Bosch Premium part number (3421). Done on 11/9/09
*Oil Mobil 1Fully synthetic 15w-50 6 qts. Done on 11/9/09 @ 248,946 miles.
*Radiator flushed. 1 gal Zerex G-05 added. Done on 11/09/09 @ 248,946 miles.

*A/C-heater control valve done on 11/5/09

*Check air valve. Done on 10/9/09

*Bosch O2 sensor replaced. Done on 10/7/09 @ 246,939

*Bosch H9DCO Spark plugs 6 total. Done on 10/6/09 *Bosch spark plug wire
set. Done on 10/6/09 @ 246,560

*Oil filter-Mobil 1 high mileage. Done on 9/20/09 *Mobil 1 Fully synthetic
extended fuel economy 0w-30 6 qts. Done on
9/20/09 @ 245,763 miles.

*Oil filter-Mobil 1 high mileage
*Air Filter- Purator air filter
*Mobil 1 Fully synthetic extended fuel economy 0w-30 6 qts. Done on
5/26/09 @ 240,000 miles.

maybe I'll recheck the O2 sensor. I'm sure the smog pump cycles on when I turn on the car or whenever its supposed to.

__________________

1990 190E 3.0L