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  #1  
Old 05-01-2006, 06:30 PM
Ron in SC's Avatar
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Question 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?

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  #2  
Old 05-01-2006, 06:39 PM
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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.
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  #3  
Old 05-01-2006, 06:51 PM
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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.
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  #4  
Old 05-01-2006, 07:54 PM
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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.
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  #5  
Old 05-01-2006, 08:07 PM
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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.
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  #6  
Old 05-01-2006, 08:27 PM
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Quote:
Originally Posted by Ron in SC
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.
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.
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Old 05-01-2006, 09:21 PM
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Quote:
If you have not replaced the cap and rotor in all these 100,000 plus miles, they need to be replaced.
I replaced them when I got the car a few months ago, so that would not be the problem.
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  #8  
Old 05-01-2006, 11:41 PM
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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.
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  #9  
Old 05-03-2006, 04:59 AM
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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
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  #10  
Old 05-03-2006, 06:03 PM
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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
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  #11  
Old 05-04-2006, 12:27 PM
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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 !
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Old 05-04-2006, 06:32 PM
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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
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  #13  
Old 05-05-2006, 01:05 PM
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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.
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  #14  
Old 05-23-2006, 03:59 PM
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Quote:
Originally Posted by 89-300ce
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
Where exactly is it located? I have a similar issue...
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  #15  
Old 05-23-2006, 05:16 PM
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On a 560sl it's

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

JB

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