Hello Everyone,

Thought I would update the thread...

I purchased a used EHA off of eBay. When it arrived I was a bit depressed as it looked like the brass cap screw that people remove to get access to the 2nd screw which actually adjusts the EHA was tampered with.

I swapped it out with my current EHA and installed 2 new green colored o-rings while I was at it. (I will post a write up on how to replace the EHA when I get the chance.)

After I changed the EHA with the 'new' one. I started the car with my multimeter set to duty cycle and the positive (red) probe in port 2 and the negative (black) probe in port 3.

Key in, ignition position 2, engine is off:
69.2%

Engine started, cold engine, idling:
49.2 to 49.8%

Engine warming, engine entering closed loop cycle:
Initially fluctuating between 49% and 65%, then eventually got 'lost' so to speak and by 2-3% increments per second worked its way to 92.3 - 92.7% and stayed there. (Note I was not touching the throttle at any point.)

I turned the engine off, removed the air cleaner, used a 3mm hex key to turn the tower mixture screw, replaced air cleaner... etc. (Repeated this procedure 4 times)

After a total mixture screw adjustment of slightly less than 5/8 CW...

My new numbers with the new EHA installed:
Cold engine idling: 49.2%
Hot engine idling: 44.3% to 55.4%
Hot engine revving (2500 to 4000RPMs) : jumpy as hell, but between 45 and 55%!

No longer does the mixture work its way to 0% or 100% anymore when revved. With the old EHA, I was able to stabilize the hot idle mixture between 45 and 60%, but when revved the mixture would work itself to 100%.

Replacing the EHA appears to have fixed my problem with the mixture when revving with a hot engine. (Please read above posts.)

Now I am going on a highway run for an hour and will take the car for an emissions retest. Today is my last day for a free retest at my emissions place. If I dont pass, it might be the cats or something else. My plugs are only 10K old, my cap and rotor are 25K old, my wires are 30K old. Engine seems to run great. I am going for a test drive to see how this new EHA makes the engine behave.

Wish me luck! Also, thank you for your assistance!

__________________
2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)