I have just recently purchased a 1985 380 SE with approx 105k on the odometer. During the last three or four weeks that I've owned it, it has stalled on me during periods of idle. It seems to happen regardless of whether warm or cold. In fact, the first time it happened to me, the car had been running for at least an hour.

Most of the time, the vehicle will just stop while at a stopsign or a light while idling with my foot on the brake. It seems to be idling at just under 500 rpm by the tach. On one occasion, it stalled while decelerating.

It does not do it each time, and in fact has probably only done so about a dozen times so far.

Where should I look first on this ?

AH! Join the club. My 1985 380SE does this too, but stalls when stopping, slow turns, or placing in gear when the engine is warm/hot. Its been doing it for a while.... does it worse in hot weather months. I have been told it could be the following..... idle control valve, vacuum line leaks, manifold gasket leak (GASP), etc.

I have given up on mine. One local MB repair shop said for me to check for airleaks with brake cleaner (on cold engine)... acted like they did not want to get their hands dirty on a 22 year old MB. Another I called said they charged $65.00 per hour and it may take hours to find out what is wrong. SO, I have given up. I have a bigger problem now anyway, as something blew out of my steering system and all of my fluid is out... to the "regular" shop tomorrow or this week sometime for that.... maybe they can find out why it stalls. However, the big problem now is that I have a rough idle when cold... it splutters and "chokes" itself. I get gassy smelling smoke and missing until the engine warms up... even then it still will occasionally miss when the gears change.

Sorry I could not be more help.... do a search on here. It seems to be a common problem, but I have yet to see a post on there that will tell you the problem. There are always answers like.... it could be "this", or "that", or "this", or "that", or "this", or "that", or "this", or "that"..... you get my meaning?

After the stall, will it restart?

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

No one can diagnose a problem like this over the internet, because there are several possible causes. And if you can't catch it in the act, it makes troubleshooting even more difficult. And there are no diagnostic codes.

Possible problem areas:

- fuel pump relay
- idle control relay
- idle control valve
- throttle position switch
- lambda (mixture control) system

Try a search. Lots of posts on each of these.

A good basic health check is to see what the on/off ratio is doing. You need a meter with a duty cycle reading or an analog dwell meter. Again, lots of posts on how to do this.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Yes, I was going to say try jumpering the FPR with a paperclip after the stall to see if that remedies the problem. I have personally experienced the same symptoms you describe and it turned out to be my FPR. I replaced it and have put about 5,000 miles on my car and it has never stalled again.

Also the suggestion to check the duty cycle is great; will give you an indication if the on/off is working properly. If it's not, it can exacerbate other issues.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Fires right up with a single flick of the ignition.

Same symptom I had, in fact I could often slip into neutral and restart while coasting. Then one day it just wouldn't restart again and I had to jumper with a paperclip to get the car back home. You want to avoid this situation.

Do a search - you can crack the relay open and check the solder connections which often fail due to age and/or heat/vibration. Resoldering them can give them a new lease on life. In my case, the previous owner told me he had already resoldered a couple years prior so I just went ahead and bought a new one. I think it was about $100.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Chuck,
Indeed, no one can reliably diagnose such a problem over the internet, but the collective knowledge here is impressive and I appreciate the ideas of where to begin. I also greatly appreciate your willingness to share.

Check it out:

1985 380SE W126 Stalling - Fuel Pump Relay ?

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

gmercoleza.... so I see it was indeed the fuel pump relay? Where is this part located and how difficult to change? My car also misses, splutters and billows out smelly, gassy smelling smoke from the exhaust when the engine is cold. I wonder if the FPR would also cause those symptoms?

The part is located in the fuse box under the hood. It is made of black plastic and dimensions resemble a slim pack of cigarettes. Replacement is very easy; just grab it and pull it out. In my case an intermittent stalling was cured by replacing this part.

What you describe << smelly, gassy smelling smoke from the exhaust when the engine is cold >> seems more mixture-related.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Thanks. Sounds simple enough. Yeah, knowing my luck, it is something not as simple. When warm, I do not have that spluttering/smoke, but it has gotten worse to where it seems to have a slight miss at idle when warm.

Maybe that guy can find out what is wrong with that too.

I think I've found the part in performance parts catalog. Now to see if I can find it in the local parts catalog. Thanks for the pointers.

I would also MOST DEFINITELY clean out the idle control valve. Its a little metal barrel shaped device with hoses going to it, in front of the air cleaner. It gets crankcase fumes drawn through it and gets very gunked up. Remove it and blast the insides with carb cleaner.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

Are you referring to my car or to "spqrzilla's" car?

How do you remove the ICV?