Every once in awhile I will come to a stop or slowly go around a corner and the car will stall. Then it will be difficult to start up. Normally the car starts up very easily. Any ideas?

Intermittent Stall
 

There must be a thread on this somewhere. You might check. When my 300E was first new to me, my tech mentioned that I might run into the mysterious "intermittent stall" syndrome. He said that Benz had sent around a service bulletin about this subject and then printed off a list of possible causes from his handy-dandy computer which if you would like, I will reproduce here.

I thought I had run into the problem once because my car stalled a few times but always started again. Then the fuel pump relay became a fatality. You might check that out, too.

dtanesq
 

Please post the list of possible causes from the service bulletin for all our benefit.

My pleasure
 

Quoted from the shop print-out my tech gave me (gramattical errors were not corrected - I proofed this very carefully for accuracy of reproduction):

"The owner states that the engine dies intermittently when coming to a stop. (Maintenance note: This problem has been around for a long time. Mercedes-Benz has published several bulletins about the problem. See Diagnostic Directory 07.3-88043/30T93031/07.3-91043/54-89101/AF07.32-U-6701A & TIN 07.3/6. There are about a dozen things that can cause the engine to die. We normally see on about 3 or 4 cause all the problems. Sometimes there can be more than one of these things acting up at the same time. That's when it gets hard to find the problem. The components that cause the most trouble are the fuel pump relay, the flywheel position sensor, and the over load protection relay. We have also seen the Hall Effect sensor, the tachometer, the distributor cap and rotor, the ignition coil, the oxygen sensor, the ignition module (see D/D 15-89041), the idle air valve, temp sensor, wiring harness, EHA valve & the electronic accelerator (see D/D 30T93031). We try and replace the most common things first and if that doesn't take care of it then we get into the more unusual components.)"

Again, upon replacement of my fuel pump relay, mine hasn't stalled. Before I purchased mine, I drove my neighbor's 87 300E as a sort of test-drive-by-analogy to see if I'd like the model. I drove it exactly as he suggested (hard-with apologies to Hottee18 for all the advice we old guys gave to him on that subject awhile back) and I went red in the face when it stalled after coming down quickly from a very hard acceleration run. The owner had never had it going that fast and it had never stalled before. I cleared my throat, it restarted and we drove home. It hasn't stalled on him since. Probably undiagnosible.

Good luck.

Thank you David! I haven't had that happen, but a printout of this thread just went into my service record book for future reference.

Stalling Problem
 

Thanks to David for posting suggestions.

I have a very similar problem with my 88 300E. It usually stalls in the first 5 minutes after a cold start, and then doesn't stall again. After restarting the idle increases a couple of hundred rpm at idle!

This seems to be a very common problem to 300E drivers, and one would think some very common solutions are out there. I'll let you know if I find one.

Try this, use regular unleaded rather than premium.

Regular Unleaded
 

THAT was another discussion I had with my tech, but it related specifically to the 300E rough idle issue. I've written it elsewhere and it can be found on this forum, but Mercedes has changed the injectors on these cars and if you have the old ones, you may have a rough idle condition due to the spray pattern.

Sometimes ignorance helps
 

Wow. Pretty esoteric stuff. My car was behaving exactly the same way. It was a few months after buying the vehicle used and I didn't know Mercedes from Adam (I have always owned BMW). I did two incredibly simple things that fixed the problem forever, and I have no idea which one of these two was really causing the stalling episodes, but I have my suspicions…explained later. First I removed and reinserted the large rubber-headed electrical connectors on the left inner fender. Then I removed the battery terminals. The contact areas of the terminals were black. I cleaned the battery posts and the inner surfaces of the terminals with the special terminal cleaner brush, and sprayed Exide Battery Protector (the red stuff) on the contact surfaces, and reconnected the terminals. The stalling has never happened again. I suspect that there is a component that goes haywire if the battery cables momentarily lose contact with the battery.

Same problems here!
 

Hi Steve,I just encountered exactly the same stalling phenomena several weeks back,and it only happens when I come to a stop or slowly go around a corner and the car will stall. And warm-starts are always more difficult than cold starts,took longer cranks to get the engine fired up.

I have been reading thru all the threads on this forum as well as others,and it seems like there're really a dozen of likely causes,ranging from simple tuneups which we have overlooked to problems lying with more unusual parts as someone as mentioned here in this thread. And I am getting pretty frustrated because my mechanic doesnt seem to know how to diagnose such a problem.The last time my car stalled last week,I'd it towed immediately to the workshop,only to discover that it was performing alright again.Sigh......

My mechanic suggests I change the "Idle Control Valve" (aka Idle Air Valve/Idle Control Unit/Idle Speed Stabilizer/Idle Speed Regulator" etc.Pls correct me if I'm wrong.And another fren suggested checking the vacumm hoses for leaks or clogged areas.Maybe we can start from here.I might replace my injectors next if the stalling persists.

Then again,it depends on the model of your car.Mine doesnt have an oxygen/lambda sensor,so troubleshoot it according to your car's parts.And of course we need experienced techs from this forum to advise us if they share the same car model and stalling problems.

I'm posting a new thread asking for the part number for the Idle Control Valve,so you might want to take it down.Hope to get it resolved soon,otherwise I'm always feeling insecured whenever I'm at a traffic junction or a carpark.

:(

Random stalling?
 

My car was randomly stalling a few days ago while I was on the highway and at idle. I cleaned my battery terminals and replaced all of my fuses hoping to fix the problem. It has worked for the past 250 or so miles. What is it about dirty battery terminals that causes the car to stall(white buildup)?
thanks
doug

I too have suffered this phenomena, but in a 1984 380SE.
The only solution I have found is a pitiful solution called braking with the left foot while maintaining slight gas pedal pressure. As the problem is so infrequent and is solely at very low speed, this switching of the feet at the last moment has become nearly second nature.

This car has been in the family for 14 years and in the early days, much as attempted by the local dealer. The idle speed control valve and the brain have been replaced several times with no long term change.

However, on several attempts, the old carb cleaner in search of an air leak revealed air leaks in a vacuum hose and replacement of same did fix the problem for some period of time. However, the problem always returns.

Over the last two years, the car is sometimes slow to start when cold despite brand new injectors.

I clearly intend to try the above mentioned potentials but must first focus on the new problem that I posted on the Tech site.

Thanks for the info.

Dwight

The document in the diagnostic directory (I don't have the number at home) has a very good fix for a huge number of these problems. It involves disconnecting the wire from the ECU to the starter through the NS switch. By taking the end going to the ECU and grounding it the idle speed is increased. THIS ONLY WORKS ON 86-89 300e. The way it normally works as originally wired the idle increase is removed when put in gear.

This works for those models that the idle is unusually low, fairly common.

? same for 190e-2.6
 

I had the same problem with an 89 190-2.6 - hot stalling and undrivability to the point of danger. No one could fix it and it was eventually taken off the road where it sits today.
Since the motor is essentially the same as in the 300 could he same problem list apply?

My problem was fixed by replacing the distibutor cap. Previously the plugs and wires were already replaced. It has not stalled since. Just thought I should update you guys.

Thanks for all your input,
Steve

As you can see there were a number of items posted that could cause the stalling episodes, and at least one of them was the solution. For my 300E, it was the OVP.

Glad you got the problem solved.

Steve,
I have a '85 500SEC. It had/has a stalling problem also.
What I have found out is: The fuel pump wasn't getting any voltage. That is the fuel pump relay.
I popped the cover off the relay and you could visibly see the contacts on the solenoid close.
At last, out of frustration, I was handling the relay and I noticed that the support for the solenoid was loose from the circuit board!! There are two solenoids in there. The small one is the over-voltage. The large one is the fuel pump.
I took my soldering iron, and re-soldered the back of the support. Apparently, the support is the ground. It was "cold-soldered" at the factory. It also has a bit of corrosion on it. That is because, as the current flows through it, it developes disimilar metal corrosion.
Anyway, just re-solder it and plug her in.
I had bought a used one, in the beginning, and this one had the exact same problem. I fixed both and carry both. Good luck, John F. '81 240D; '85 500SEC.

I had the same problems with my car... to the point that I didn't even want to use it anymore. It sat in my garage for two months before I came back to this forum and got a reply from MBDOC (thanks, again!). Anyway... here's my story.

Car started stalling intermittently. The red LED in the battery compartment (next to the diagnostic terminal) would light up. It could be reset by removing the battery terminal, but the problem persistently came back... sometimes after 10 minutes! So, the following things were done:
1) cleaned filter... suspected bad O2 sensor. No good.
2) Replaced O2 sensor. Still no good.
3) Brought car to reputable shop, wherein they began to tear into the engine. Car used to be my brother's, and he did ZERO maintenance on it. They replaced the distributor cap, rotor, spark plugs, wires, and then.... changed one of the fuel pumps (mine had two). Dude said, "Car's all good." I took the car out and as soon as I got on the freeway.... put-put-put.

5) Garaged the car and cleaned all the electrical contact... still wouldn't run... and now I am livid. The car isn't even idling.
6) Changed the famous OVP. That didn't do it. The car sat in the garage for two months.
7) Went back to the forum and re-aired my problems. MBDOC said... "crank angle sensor."
8) Took the car to the shop and repeated what MBDOC said. They called me back later and said that was it, including a leaky Fuel pressure regulator (I knew I smelled gasoline).

Problem solved....

I had a rough idle/stalling problem with my 88 300TE (actually bought it for my mother) -- after a long overdue tuneup (plugs, wires, cap, rotor) it was better, but not fixed.

Having grown up in the age of carburetors, I started looking for what (to me) was obvious -- vacuum leaks.

Evey piece of rubber hose in the engine compartment was shot -- some the typical MB "soft and shedding" and others rock hard and leaking. The worst ones were the connection for the vaccuum modulator and the one for the MAP sensor on the firewall. Replacing all the rubber ends on the hard vaccuum lines helpled, but didn't cure the idle vibration, nor the occasional stalling. Did fix the hard shift problem.

I then looked at the idle valve, and found the two large hoses to be so hard that they were actually loose on the fittings. Replaced them (inner one is a big pain!) and finally cured the problem.

Still have an occasional stall, but I think that is the idle valve itself -- I didn't clean it. Usually happens if one stops from speed rather abruptly.

It's worth the few minutes to check these hoses -- they are accessable with the air cleaner housing removed (and check the mounts while you are in there, two of mine were separated!) -- if the hoses aren't pliable, replace them. You will probably need to adjust the idle mixture afterwards.

The reason the OVP and bad battery contacts can cause idle problems and stall is that the mixture control system is powered off the same circuit, and goes off-line if the voltage drops too low or too high, causing an over-lean condition.

Peter