SSS or...?? M103
 

Hey Guys,

First of all I would like to state that I have just spent a day & a half in the archives reading up on SSS and, while my brain is addled with information, I don't feel like I have any solid leads based on my rather unique circumstances.

(Car is my 1991 300E, M103, 165k mi, very well maintained.)

The circumstance: The stall is very specific & very repeatable. I have to be going 30-35mph or better (say, @ least in 3rd gear). I then have to brake fairly hard all the way to a stop; If I brake fairly slowly to a stop, no stall. If I brake hard to a stop under 30mph, no stall. I did get it to stall once by braking hard to almost a stop (5-10mph?) at a yield and found myself stalled & drifting into oncoming traffic. :eek: (I literally made that face).

It also does start immediately every-single-time after a stall and take off again fine.

Based on what I've been reading, it sounds like the car is having a problem going from 'drive' into 'idle' mode. (Please confirm or argue this point :D).

Otherwise she idles fine, runs great, and is the phenomenal German auto she's always been. The OVP was replaced a few years ago (stalling issue that turned out to be the Voltage Reg) & the EHA was replaced a few months ago (old one was leaking). All other filters/tune-up parts have been replaced in the past few years as well.

Based on my specific circustances what's my best bet for first attack? ICV? Vac Leak? Crank position sensor? Sell for parts & put all the money into my SL?

Thanks!

Highly likely that its the Crank Position Sensor. Does the car throw any codes?

I'd replace the sensor and see what happens. My 300E was doing the same thing, sensor replacement solved it completely.

I haven't checked for codes. I didn't think I could on an MB... I haven't checked a code since my POS GMC van in the mid-90's...:rolleyes: :D

Can it be done w/o some ridiculously expensive Bosch tester?

Check the plug/connector by the battery, some of them have a LED and button to check codes.

Do you have a pic of this?


And in the meantime, sans codes: Any opinions out there as to the probably culprit?

Was it the front or rear CPS on your, pawo?

(After a little more reading, I assume it's the rear, as the front doesn't do much...)

Hey 350,

Pardon my ignoramusness but....what is SSS?
Acky

Correct on rear. The front does not have any influence on the engine. Its for the tachometer?

SSS: Sudden Stalling Syndrome.

It sounds like that is one of it's responsibilities. I'm sure it has some other obtuse function. And, just for reference, MB calls the front one a "TDC Sensor" and the rear a "Crank Position Sensor".

And I should have listed the definition of SSS at the beginning for anyone who hasn't had a W124 long enough to experience it yet. :D

Some interesting test results so far. I'm getting some weird results from my Throttle Valve Switch. We'll call it a 'Person of Interest' at this point as opposed to a 'Suspect' for the time being, but I'd appreciate any helpful input:

http://www.peachparts.com/shopforum/tech-help/253745-throttle-valve-switch-question-m103.html

i think its the small speed sensor fitted on the back of the speedo, it sends the speed from the speedo to the ECU. it enables the ECU to know when to switch from the over run mode into idle mode. to check it, unplug ur injection ecu behind the bat. drive the car, if the stall goes then its most probably the speed sensor. should set u back abt 50usd to buy it, u can change it at home. the new part is better built as a fix for this issue.

Just wanted to post a quick follow up here:

I originally replaced the TDC sensor and the problem lessened a bit, but I was still stalling occasionally.

Later, I started noticing that I was having trouble with my idle dropping with the A/C on at intersections. After some thinking & some digging I started to see that a faulty ICV valve could be causing both of these issues. I didn't muck about with cleaning the ICV & just replaced it (not too expensive from Phil).

All better! No more stalling. No idle dip at intersections w/ A/C on.

I know everyone's SSS seems to have a different source, but I wanted to follow up with my experience on this particular M103. (It's actually my belief that all SSS problems are caused by multiple aging parts/sensors in the M103's complicated idle control systems.)

My M103 had bad sensors and ran like crap until I replaced them. It has been perfect ever since. My idle control valve was stuck too, but I found a good used one, cleaned it, and it has also been fine ever since.

A 91 might not have that unless it's a California car.
Regards, Eric