has anyone heard of an "hall sensor" being on a 88 2.3 190e? If so,what dose it do and where is located?

Hall-effect sensors are quite common on newer vehicles.
They are used primarily for sensing crankshaft position, camshaft position, etc.
Prime purpose is to synchronize & " fire " ignitions systems & fuel injectors.
Sorry, can't tell you any specifics ( location or purpose ) on your particular car.
This is what it looks like:
http://img.eautopartscatalog.com/live/F601051836BOS.JPG

Here you go: http://63.89.49.212/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1R510G7PR1RD1969Q6&year=1988&make=MB&model=190-E-004&category=F&part=Reference+Sensor

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2007 C 230 Sport.

Thankz, Just had my tranning changed(for no reason but profit)anyway I did see this sensor. Can you provide more info on location?

According to FastLane's description, 1 is at the flywheel & the other at the crankshaft pulley.
Question is which one do you need?
May have to consult with a real expert, not a shadetree mechanic like me.

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2007 C 230 Sport.