This is an '89 300se and I've been chasing this problem since I bought the car in March. It always takes at least 2 tries to start it, sometimes 10 times or more. It starts, revs up then the rpms drop to zero and it stalls. When it finally does keep running it will sput and sputter for a few seconds before settling down to a normal idle.

There have been occasions when even 10 or more tries was not enough. On those, it will start if I hold the throttle open a bit. But if I take my foot off it will stall. Even if I hold the throttle open for several minutes before releasing it. The only way I keep it running then is to ease the rpms down to where I can shift into drive and drive it for a few minutes. Eventually it runs fine, but if have to stop within those few minutes it stalls. It seems to need that sput/sputter bahavior before it will run right.

It is much worst on a hot start after it sits for 30 minutes or more.

I replaced:

• Distributor cap & rotor
• Spark Plug wires
• Spark plugs
• Fuel pump
• Fuel filter
• Fuel accumulator
• Hoses leading to and from the ICV
• All fuses
• Air filter

I've tried jumpering the fuel pump to take the fuel pump relay out of the equation but it did not make a difference.

Everything on this car works, and once started it runs and idles very well.

Can anyone give me a clue where to look next. Thanks.

__________________
2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

check and see if the fuse in the ovp relay is blown.it sounds as though you are starting without the benefit of power to the fuel injection computer or "limp home mode".

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

suggest pull out the over votage protection relay, clean the pins on it and the fuse on the top side . same for the fuel pump relay . the solder joints in the OVP do open up like it did on mine unit.
Remove and clean the ICV thoroughy , check for operation by momentarily applying 12 V to the pins and kistening for the operational click and monement.
keep us updated
regards
mak
89 300se

Don't forget the crankshaft position sensor. This one got to me once, and it is cheap/simple to replace, and for an older model, cheap insurance, even if it is not causing the immediate problem.
Hope this helps you, like someone on this forum helped me.

I checked the OVP relay fuse and it was fine. However, I had a spare OVP relay I bought in a box lot of various relays and switches back when I had the 380 SEL. It didn't fit it the older car but it's the exact part number to work on this one. I cleaned the pins and plugged it in. Last night it seemed to do the trick, but today the car's behavior has been pretty simular, though not as severe. I'll see how it does over the next few days.

The idle has always been good, and I did clean the ICV with carb cleaner when I changed its hoses, and that did stop the idle from "hunting" from time to time.

Thanks for the CPS suggestion. I'll try that next.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

I went into Fastlane to order a new crank position sensor. I expected to find one part listed, as that's all the repair CD shows, but discovered two parts listed. One says, "located at front crank pulley, W0133-1613779." The other is "at flywheel, W0133-1603956." I thought I could sort it out by checking another parts supllier's website but found the same confusing listing, plus that website also listed a camshaft position sensor, which I can't find on the repair CD. Then I checked another supplier and found only one CPS listed. ?????

Can anyone help me sort this out. Does my car have two crank position sensors and does it have a cam postion sensor as well?

The car is still up to the same behavior after swapping out the OVP, so that pretty well rules it out as the culprit.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

Here's my understanding of the M103 motor of your vintage. There are 2 sensors. The one you want is at the flywheel in back down by the bell housing. The other one up front is, I've been told, for diagnostic rather than operational purposes, by providing the so-called TD signal to the EZL. No cam sensor in '89 (I think). The condition of that flywheel sensor is very easy to confirm with your ohmmeter though, so do that before investing in a new one.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

have you hooked it up to a computer? Does it have an odb2 or 38 pin? THAT would be my very first move. then start over, start simple and move forward from there. Its getting spark, but it stalls, fuel system integrity? fuel filter new? Injectors clean? again, I'm just shooting in the dark.

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99 E3204matic wagon
99 CLK 430

This sounds a lot like what our 1989 190e did (similar engine, same CIS-E fuel injection).

It would start, then stall. Eventually it would run. Sometimes it would only keep running if the revs were kept high. It became undrivable.

I replaced the cap, rotor, OVP relay: all wasted money.

The problem was the potentiometer on the front of the fuel distributor / airflow meter. The carbon tracks in the potentiometer tend to wear out, especially at the idle position (our 190e had 200,000 miles on it). When the potentiometer is faulty, it sends a spurious signal to the computer, which then has a nervous breakdown, and can't make up its mind how to control the idle.

The part is no longer availablefrom Bosch, or anywhere, it seems. They will sell you the whole unit for $1000 plus. If you look in the archives, it seems that this was quite a popular repair, before the part became unavailable three or four years ago.

Solution: a new fuel distributor / airflow meter unit, from a wrecker, off a low-miles 300e. Even then, the EHA needed tweeking (delicate adjustment of the tiny allen-head screw behind the brass plug), to get the right pressure differential between the upper and lower chambers of the fuel distributor. Now it runs beautifully.

This all became apparent only after I made up adapters, for three meters at once, to measure EHA current, idle valve on-off ratio (dwell), and the voltage on the potentiometer. And, of course, I eventually neede the CIS-E fuel pressure tester to measure the differential presure.

Good luck!

Andrew

Any conclusion to your hard start/rough idle condition? If not, you've got to be close, b/c you've practically replaced everything. Just re-read the thread, and didn't see any mention of fuel pressure regulator. I've never had one go bad, but it could affect hard starts. Just thinking out loud.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

Member Ajme suggested I take a look at the airflow potentiometer. What he describes his car doing sounds very much like what I'm experiencing. My car runs fine except at idle right after it starts. I was able to find what I think is a good used replacement part on ebay. As soon as it gets here I'll install and adjust it and report on the results, probably about the middle of next week. Thanks for following up. Hopefully this will do the trick.

__________________
2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

Hope this helps, it tells you how to adjust the airflow potentiometer: http://sg-motorsports.com/AFS%20Pot%20write-up.htm

I replaced mine and it solved my surging idle issues and difficulty starting issues. I've still got a little hesitation when I start my car but something I can live with as it runs great otherwise. Good luck!

EDIT: And no, you cannot change the timing by rotating the distributor on the M103s.

[QUOTE=bolomiester;2216678]This is an '89 300se and I've been chasing this problem since I bought the car in March. It always takes at least 2 tries to start it, sometimes 10 times or more. It starts, revs up then the rpms drop to zero and it stalls. When it finally does keep running it will sput and sputter for a few seconds before settling down to a normal idle.

There have been occasions when even 10 or more tries was not enough. On those, it will start if I hold the throttle open a bit. But if I take my foot off it will stall. Even if I hold the throttle open for several minutes before releasing it. The only way I keep it running then is to ease the rpms down to where I can shift into drive and drive it for a few minutes. Eventually it runs fine, but if have to stop within those few minutes it stalls. It seems to need that sput/sputter bahavior before it will run right.

It is much worst on a hot start after it sits for 30 minutes or more.

I replaced:

• Distributor cap & rotor
• Spark Plug wires
• Spark plugs
• Fuel pump
• Fuel filter
• Fuel accumulator
• Hoses leading to and from the ICV
• All fuses
• Air filter

I've tried jumpering the fuel pump to take the fuel pump relay out of the equation but it did not make a difference.

Everything on this car works, and once started it runs and idles very well.

Can anyone give me a clue where to look next. Thanks.[/QUOTE

Without going into too much complication, this is what I think- Your ingition timing is off. You might try to retard or advance the the timing by rotating the distributor. If that does not resolve the problem then you need the check the timing chain stretch test and if timing chain is stetched beyond limit you need to put new timing chain. Agian this my opinion that your broblem is ingintion timing way off. This can only be fix by new timing chain with camshaft and crankshaft alignment.

IF YOU DO NOT TAKE CARE OF TIMING CHAIN SOON, YOU WILL END UP BROKEN TIMING CHAIN AND ENIGNE WITH BE TOASTED. YOU NEED TO PUT NEW ENGINE TO FIX THIS PROBLEM- COST- MORE THAN 2000-5000 DOLLARS.

Sahai

Sahai

I did not know you could adjust the timing on an M103 by rotating the distributor.

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2012 E350
2006 Callaway SC560

He had already replaced the OVP relay so he is good there, the fuel pump relay isnt a bad idea but I am buying on it being a bad cold start valve. Try going to www.benzworld.org and looking up cold start valve. If you say once running its fine I am betting your cold start valve has a leak. Since it gets shut off when its at operating temp and you say after it cools off 30 min after shutdown it happens again It really sounds like that.

Good luck hope this helps.