I have a '89 300SE that has a slight hunt (idle fluctuation). I disconnected the three pin connection to the throttle valve and the resitance reading through the idle connection fluctuates slightly. I have replaced most all the vacuum lines including the inlet and outlet to the idle control valve (which I cleaned while removed), so I dont think I have any vacuum leaks.

I think the problem may be dirty/bad contacts in the idle contacts in the throttle valve switch. My question is, is it possible to disconnect the idle valve switch, and jumper the center and forward connectors simulating a good contact and see if the idle stabilizes, or would that damage the ECU?

While replacing the fuel filter, I checked the diaphram on the fuel accumulator and it is intact.

Thanks.
Jeff

You can jump the wires to the ecu from the idle switch. Make sure that you are on the correct wire though. I would use an ETM.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Thanks, I'll give it a shot.