I'm having the same stalling problem with my '88 260e. It started a couple months ago and is getting worse. The cars runs and idles fine but will intermittently stall usually when coming to a stop or rounding a slow turn.

Following Benzmac's advice here, I took the pot out and cleaned it. It was spotlessly clean but had some wear spots in the idle range as predicted. I ordered a new pot from olyparts.com ($80) and we'll see how that goes.

One thing I learned when reinstalling the pot is that the alignment is VERY sensitive. Even having scribed the location the car ran terrible after I reinstalled the pot - idle hunting up and down and stalling really bad. I did some carefull checking of the scribe marks and got the car driveable again on the second try.

Garth, I have a feeling you did the right thing by replacing the entire flow meter. I think replacing the pot is going to take some real fine tuning.

For more information on replacing the pot there is an excellent thread with pictures. Do a search for "airflow meter pot source".

John

It was definitely the potentiometer. Its been two years now and the car is running like a champ.

Now that its been problem free for a couple years, I think I can convince the wife on new shocks.

Good luck!

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Garth Gillespie
87 300E
92 Audi 100CS Quattro

Hi,

I have a 89 300te that I love, and it had the same troubles of rough idle and stalling. And yes it was the combination of the resistor and the hoses on the idle valve leaking air. The hoses were inexpenseve $18 but the resistor just cant be found so it seems. So I resorted to my 35+ years in electronics and made a simple repair to the resistor. I cleaned the resistor NOT with an eraser but with some typeing paper as it doesnt leve rubber in the carbon trace and is less abrsave, where the element was worn thru I made some resistive ink and carefuly painted the worn spot lightly. As we are talking of a spot that is less than 1/64" the over all resistance is not affected much. I could have just touched up the spot with a soft pencel but opted for the ink insted for a longer lasting repair. Bing Bang Boom IT WORKED and I'm Happy again. This whole operation took less than an hour and two beers. Total cost some time

I was trying to think of some way to bridge the gap in the carbon trace but didn't know about the resistive ink. Where did you get it?

I too have run the gambit trying to get my twin daughters 300E from stalling. I have replaced fuel filters, fuel pumps, plugs, etc..., yet the sporadic stalling continues. It sounds like the air flow sensor POT (i.e. variable resistor) being worn is a likely suspect.

I have cross-referenced the air flow sensor and there are no current replacements from many manufacturers (even though these devices are used for BMW, Audi, and other vehicles as well). I found a shop in Berlin that would sell refurbished units for 177 Euro, but that equated to $246 U.S. (and you had to send in your unit). Gouge...

Since I would bet that they are simply repairing the units with resistive / conductive ink / epoxy as well, I too (like a previous post), took my 25+ years in hardware and software development in that direction and found Stan Rubinstein Assoc., Inc. They have the least expensive solution in the quantities that I need (other sites started at $75 for more than is required). I have purchased both ink and epoxy to determine the best solution and will post my findings here (product is in transit as I write).

Their site is store.sra-solder.com and I ordered 14g of their 2-part Silver Epoxy as well as a Silver Print Conductive Pen. I believe that the epoxy will be a more durable solution but wanted to keep my options open. Combined parts and shipping ended up around $61, so it is worth the trial to me.

Again, if (/when) it works I will post pictures of the steps that I performed. And should it be appropriate I would be happy to help others if they help with the cost of materials and shipping (I am a computer professional and would not be interested in making money from people in a forum that has helped me).

Stay tuned...

My 1988 300E has had the intermittant stalling problem for years as well, and recently has started running rather roughly at lower idles. My car will stall coming to a stop or turns, but it will also stall at highway speeds. Sometimes I can put it in neutral and turn of ignition and fire it right back up, but other times I have to pull over, park, and let it sit for anywhere from a few seconds to a few minutes before it will restart. Usually it won't stall again for weeks to months. Sometimes, it will go through a period where it will stall a few times rather quickly, like minutes apart, but this is unusual.

The rough idling part is rather new.

When I am sitting at a stop the vacuum gauge is about halfway and fluctuating. If I turned on the AC it will really go back and forth, hunting up and down.

I definitely will check out the air flow thing, but any other ideas?

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1999 Mercedes ML320
2002 Mercedes 230K

I'm really interested in hearing how the conductive paint works on repairing the airflow sensor pot.

I see that I was having a problem back in 2003 when I replaced the sensor pot in my 260e. That was 5 years ago and I have not had a problem since. My concern now is that my wife's 300e will be due for one soon. She said the car stalled on her a couple times in the past few months but restarts with no problem. I tried searching for a source to buy a replacement with no luck. Wish I woud have bought two back in 1993 when I had the chance.