Should this happen?
 

I've been trying to check on what could be an OVP problem with my 88 300SE. I susupect the OVP because the ABS light occasionally flickers and there is an idle roughness that has stalled a few times and stumble on initial acceleration.

I started the car and when I pull the 10 amp fuse the car dies. It did this 3 for 3. Is this normal or a problem?

The car should do just fine without any OVP at all. There are two ways that the OVP affects the running. First is that the KE controller handles mixture correction. NOW this is IMPORTANT: a warm running, correctly adjusted system, will idle as good or better if the control unit is disconnected (same as no OVP).

Second the KE controller handles idle speed control. Again the designers of the system built it to do just fine, broken.

SO, if yours isn't playing this way it would be logical that it has something to do with one of those activities. I would try disconnecting them individually and see which acts the same as removing the OVP fuse. To do this disconnect the EHA for the mixture correction part and separately disconnect the idle valve. if pulling the fuse causes the car to die then disconnecting these actuators one at a time should give similar results.

My guess is on the EHA. Anyone one want to say why? What has to be happening for unplugging the EHA to cause the engine to die?

2 Questions Stevebfl
 

I didn't state in my original post above that I disconnected the OVP right after I started it cold. Does that matter? I didn't know it should be warmed up.

I understand your instructions to try disconnecting the EHA and the KE controller separately to see what one makes the car die, but I have no idea where these two items are. Are there fuses listed that power each of these two? Or do I have to unplug each of these things where they are. If so, where are they and what do they look like?

I looked in my owner's manual and the fuse box cover and they don't list either one. It lists 19 fuses and none are either of these two. There are 5 silver relays but none of these are identified.

The reason for doing this warm is that once warm the only job being done electrically is lambda control.

In the conditions you now describe, you are obviously removing the needed cold running enrichment. This lasts at most about 30 seconds or untill the o2 sensor starts producing current.

The EHA is the black cude on the side of the fuel distributor - single two pin connection. The idle air valve is also a two pin connection and the valve is in between some one inch ID rubber hoses on top of the intake behind the fuel dist (I think).

Thanks, I'll check tonight by pulling the OVP fuse AFTER the car is properly warmed. Can I access the "fuel distributor" by removing the bottom of the air filter housing?