I have a 91 500sl which had a leaking EHA valve. I ordered a Bosch EHA and installed it. When I tried starting the car it ran roughly so I "Googled" adjustments to it and found several videos. Well, I adjusted it and tried several positions and gave up due to time constraints about six months ago. The car's been sitting all of that time and now I'm finally getting back to her.

The car will not start at all now. It does start with a squirt of starter fluid (spray). I understand that there needs to be a differential pressure of .4 bar between the upper and lower FD chambers, but the car needs to be running to test that. I've also tried measuring the distance the EHA adjustment screw is in and I'm 6.8 mm, roughly one turn from the bottom, per yet another video. Still no start. The will occasionally stumble when cranking like its about to catch (start) but no go.

Yes, I'm a dumb-ass and messed with the EHA screw. Any advice on how to undo my dumb-ass-ness?

More info...

Ok, I checked the diagnostic signals for the following:
MAS Controller, no error, one flash on pin 14
Distributor Ignition, no error, one flash on pin 8
Continuous Fuel Injection System, got a 17, O2 sensor shorted (possibly) on pin 3 (I can't physically trace the O2 wire right now due to my physical limitations but will look as soon as I'm able.)

I also did a duty cycle check on my X11, pin 3 ground, pin 2, signal (I think) and got a 70% duty cycle per my scope with the ignition on, in the running position. Apparently, this is ok too.

To the best of my limited knowledge, the O2 short probably wouldn't stop the car from running, it would just run rich.

Oops, my above note about says I had my scope's ground on pin 3 and lambda connection on pin 2, this is actually backwards. So my 70% is actually 30%. I've read that the way that MB represents duty-cycles is the inverse of the traditional way. So am I right in saying that getting a 30% is actually a 70%, so I'm still "good?"

So, circling back around... Can anyone please give me some advice on where the mixture screw should be set roughly for a 91 500? I'll do the fine pressure differential adjustments once the car is actually running.

Thanks in advance.