Engine shuts down while I was driving: M103
 

While I was turning a corner my engine suddenly shuts off, all dash lights go on. I turn into a parking lot and coast into a parking space. I put car in park and turn key. It starts with not troulbe and runs fine.

I wonder why it shut down. Fuel tank is full and battery has charge and alternator is charging system. Vehicle is a 1992 300TE with about 138K miles.

What might have caused this situation to occur?

Possibly a fuel pump relay going out. Do a search, all kinds of info on this site. Relay problem can be intermitant, gradually getting worse.

When I test drove it again I did several sudden stops and one of the times the rpm dropped significantly lower than they did the other times. They dropped well below 500 rpm but the engine did not die. The other times they never dropped but 500 rpm. I'm thinking maybe a fuel/air mixture issue?

Also I have the A/C compressor running it that might make any difference.

I experienced the same situation early last summer. My MB also has a 103 motor.

Turned out to be the infamous OVP.

I removed it and while holding the flap shut, shook it. I heard rattling, indicative of an worn out unit. Replaced it and problem has not reoccurred.

I also lost a fuel pump relay(a few months earlier). When this happened, car would not restart until I jumpered pins 1 & 2 in the MAS unit. Your car may or may not have a MAS. I hope it doesn't -> $500.00 @ dealer.

What you've described sounds more like an OVP issue to me.

My 2 cents.

Mike,
I have an extra MAS relay. Since I have two 1992 300Es I bought one, as a spare, for about $30 on ebay several months ago.

I'll check the OVP as you described.

Had the exact problems in my 1991 300E. Checked the OVP and fuel pump relay and all are OK. Changed the spark plugs and still no difference. Finally found the problem and it was the distributor cap and rotor. The contacts on the cap were so corroded that they just disintegrated when touched with a screw driver. If you have not replaced the cap and rotor in all these 100,000 plus miles, they need to be replaced. Mines were shot at around 100,000 miles.

I replaced them when I got the car a few months ago, so that would not be the problem.

Forgive my ignorance, but what is an OVP?

I am having similar symptoms with my 85' 380SE, perhaps the same issue? On my first trip out of the day it is fine. Typically it is my 3rd trip out for the day when it stalls out at a stop, or a slow turn. It always starts right back up. It is getting frustrating.

its TLA time!

OVP stands for Over Voltage Protection relay. It's there to protect the engine electronics from excess voltage, when jump starting apparently.

Power from the engine control unit (ECU) to the idle control valve (ICV) goes through the OVP so if its not working - they are notorious for causing problems - you lose idle control which is why your engine stalls when slowing for an intersection or whatever.

The idle control is governed by changes in current to the valve but you can check if it is working by putting a voltmeter across the terminals while the engine is running. You should see 6v, iirc, but if there's power getting to the ICV then the OVP is functioning. It may, of course, be functioning intermittently :) You can also hear the valve click into open position if you stick your head under the bonnet and get someone else to switch the ignition on but not start the car. This, btw, is known as KOEO (key on, engine off)

If you have anti lock brakes, the circuit also runs through the OVP and the ABS warning light coming on is usually a good indicator of problems with the OVP.

TTFN

I doubt this is it but...
 

Check you battery connections. I have a cable that works loose on occasion and it acts as you describe. Since it was loose but still touching, dash lights would still operate but not enough juice to run the motor.

JB

on my 260E the car would shut off after running for half hour annd then would not start again untill the engine was cold again.
turned out it was the crank shaft position sensor ! very weird but then again mercedes issues are never ordinary ! :)

In my case it was the fuel pump relay. It progressively kept requiring more and more time to cool off before a re-start.

Jorg

I think my problem was the throttle micro switch. When I removed air filter housing I observed that the electrical connector to the switch was almost completely unplugged, i.e., half of the plug was in and half was out.

Problem has not reoccurred so that may have been the problem.

Where exactly is it located? I have a similar issue...

On a 560sl it's
 

behind a small compartment door in the gloveobox, not sure where yours would be.

JB

If you haven't already, please check the Hall Effect Sensor. That little bugger can cause similar situations.

The fact that you were turning probably means nothing. More significant is the fact that you were coasting and the car stalled out while coasting (did it feel as if some unseen hand had turned the ignition key and shut the car down?).

Some M103 engines, in certain MY W124, develop a "cutting out while coasting condition." Do a search in "stalling" and/or "stalling + w124" and you will find plenty of company in your "misery."

Good luck, and if you find a cure, please report it here, so that we can add to the "knowledge library" regarding this issue.

On my 89 w124 it is between the battery and the passenger firewall behind a plastic splash shield, access from battery side. It is in the general vicinity of the OVP relay. To see if it is indeed a fuel pump relay test it when a stall has occured and it won't re-start. Have someone turn the ignition on while you listen for the fuel pump at the rear passenger wheel. You should be able to faintly hear the fuel pump humming for a few seconds after the igniton is turned on. In any case, a spare fuel relay kept in the trunk for emergencies is good policy.

Jorg

hello BENZ-LGB, I have experienced same stallings of the engine of my car. M103, 260E, 1988 and changed a lot of parts.
Was your car stalling? Have you changed the one on your car? Did it solve the problem?

How do you test the Hall Effect sensor? where is it located?

My car does not have a tempomat, do yo think there is one?

Thanks in advance.

CC, the Hall Effect Sensor is located on the back of the instrument cluster, so you need to remove it. I am not sure how itis tested. I know my mechanic replaced it and it cured the stalling at that time.

The stalling returned, several months later. My mechanic, Enrique suspected the wiring harness (yes I know I have a 1989 300TE and supposedly these cars do not have a problem with the wiring harness). Rahter than replacing the entire harness, he tested various wires/circuits that are related with the coasting-idle circuit.

The way he explained it to me, when the car is coasting, some sort of fuel management circuit cuts back on fuel, in order to improve fuel economy. The bad wiring sends a spurious signal to the circuit and it shuts off fuel supply completely.

I am not sure about hte explnation, but it makes sense that a spurious signal, while coasting, is causing theengine to basically shut itself off. When you restart the engine, it resets the system and then the car runs fine. The fact that the car restarts right away tells me that there is some sort of signal going out someplace. Restarting the car is like rebooting the computer. Right?

Since then, the car has continued to stall, but not wiht the same frequency as before. Now I can go for weeks of driving and nothing,no stalling, no problem.

The car runs well and the idle is creamy smooth (except of a VERY occasional burp or hiccup).

I have also recently replaced the distributort cap and the rotor. And I replaced the Idle Control Valve (ICV) and the vacuum hoses leading to and from the ICV.

This last repair was recommended by both my mechanic and by Psfred (who posts here regularly). Since replacing the ICV and the vacuum hoses the car has not stalled. But like Isaid it can go for weeks w/o a problem. So who knows, this may be the cure for my 300TE.

What parts have you replaced thus far?

If you list the parts/repairs maybe others can help out as well.

If you go to any Benz website, you see that many W124 owners have faced similar issues. Merkey, a new poster here, recently bought a 300TE after the PO got tired of dealing withe the stalling.

Youfigure that by now BENZ would have come up with a universal cure.

Good luck.

Check my post #13 in this thread. I think that my problem is solved, however, only time will tell.

On 89 300E
 

I had the same problem. I replaced the fuel filter, and I never had the stall again.


Good luck
Sam

Yep, time will tell. :D

There does not seem to be one specific cure. Symptoms are similar across the board. "Cures" differ from one W124 to the other. :(