Looks like I have to replace the Air Flow Meter-Potentiometer. Was able to bring the idle down to almost normal from 2000 rpm by adjusting the potentiometer. Got it into spec of 0.7 volt at idle. Bolted it gentle back up with the engine running to keep it in spec and turned of the engine. Turned the engine back on again and the RPM is back up to around 1800RPM. If I would loosen one screw and give it a little tap, the rpm would drop but it would be out of apec when reading it with a volt meter.

I'm assuming the Potentiometer is bad. Now the question: OEM Bosch vs China Ebay, the price difference is over $200. Any of you have a good or bad experience with the China cheapos?

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Jorn - sounds to me like you've done a pretty good job of working the problem.

I know nothing about Chinese potentiometers, but here's my take.

You've rounded 3rd base and are almost home. Buy one of those $15-$20 meters and see if it resolves the problem. I keep thinking about what Frank Reiner said in the 2015 post I pointed to in your companion thread. Lots of possibilities with an M103 CIS. I suspect SoCal is rich in automotive talent, but you could end up paying for things that don't solve the problem. That MAS unit ain't cheap.

If it were my car, I'd drop fifteen bucks and see what happens. If it works, you could then buy the $250+ unit from the Good-Better-Best seller in LA if you're looking for longevity.

Just my 2 cents.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I'm going through a similar issue right now.

Set your DMM on Ohms, pull off thee connector with engine off, key off, and probe Pins 1+3 - it should give you a static resistance.
Then probe 1+2 and slowly depress the airflow plate down. You should see the resistance go up/down slowly as you depress further.
Probe 2+3 should do the same, except opposite direction ie: Ohms went down on 1+2, then Ohms go up pin 2+3.

Post back what you get. Mine is pretty smooth except a few spots seem to jump in resistance, so it maybe a problem. See if you get anything similar.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Thanks, I will do that today and post my findings.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Paying for labor and parts I don't need to solve the problem is what I'm afraid off. Good point about the cheapo, not much to lose for 15 bugs besides some labor.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

You're other option is to find one from a junk yard. This might be the way to go.

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1990 190E 3.0L

I refuse to buy Chinese parts due to their lack (mostly) of QC. There are certain parts on my car that will always be OEM.
But I will buy Chinese Take Out!
Anziani
'97 Cl600 65K