Early W124: Is the EHA active during cold starts?
 

1989 300E

Should the EHA be controlling anything during cold starting? I'm trying to track down a running issue. It'll start cold (reluctantly) surge a few times and stall. If I touch the gas pedal, it'll stall. My plugs tell me I am running rich. It all started when I adjusted the EHA to try to remedy low end power issues. It started missing on #3, so I adjusted it back to no avail. Any help would be much appreciated. Thanks!

Also, while building an EHA test harness, I need to be able to test MA to ONE pole, right? As in, one pole has normal continuity, and the other runs through the meter to measure, right?

Nope, EHA controls enrichment above 2500rpms, only.

Check O2 Sensor, Vacuum Leaks, and Air Flow Potentiometer.

EHA can affect cold start and bottom end power if not adjusted right unfortunately.

Check your OVP relay behind the battery. If the fuse is blown, it's no good. You can put a new fuse in to check it, but that's not a good permanent fix/ Replace it with a new one if it's bad.