I wouldn't be too quick to rule out the EHA as a contributor to hard starts. In any case, it's easy to run the diagnostic test. Ignition off for all tests:

1) Multimeter set to Ohms. Disconnect KE control unit (N3) coupling. Positive lead to contact 12, neg to contact 10. Spec: 19.5 ohms +/- 1 ohm.

2) Disconnect EHA (Y1) coupling. Positive lead to EHA pin 2, neg to pin 1. Same spec 19.5 +/- 1 ohm.

3) Positive lead to EHA coupling terminal 2, neg lead to KE coupling term 10. This tests the wiring from the EHA term 2 back to the KE controller. Spec is <1 Ohm.

4) Positive lead to EHA coupling terminal 1, neg lead to KE coupling term 12. This tests the wiring from the EHA term 1 back to the KE controller. Spec is <1 Ohm.

__________________
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

I ran the diagnostic and everything was normal so I guess I can rule out the EHA.

Since my last post I also replaced the EZL with a very clean eBay purchase. It works fine but made no difference in the starting bahavoir.

The last couple of days I've beeen starting it with the gas pedal depressed a little. When I do this it fires right up, revs up and stays reved up until I let it idle. Sometimes it will stumble a little when I let it return to idle others it doesn't. Do this mean anything to anybody?

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

Well, you're rapidly exhausting my knowledge on the subject, but it seems that you're down to only a couple of components that could affect the idle state. The throttle valve switch (S29/2) and the airflow sensor position indicator (B/2) both supply signals to the KE controller, and the S29/2 also signals the EZL controller. The diagnostic tests for these are quick and easy to perform. Find the tests in the FSM in Group 7 under task 07.3-0121 "Testing electrical components of the KE injection system," beginning at page 111.

__________________
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 checked the Lambda setting? Not sure if I saw that somwhere in the thread.

I can tell you that I had a very similar problem and it turned out to be the rotor, even though my rotor looked and tested fine.

Are you confident that everything in the secondary side of the ignition is in good shape?

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2012 E350
2006 Callaway SC560

Check your check valve or fuel pressure, if it good trying to increase your fuel mixture maybe by quarter turn at each time(clock wire) or maybe you have some vacuum leak..(WARNING YOUR SMOG CHECK MAYBE FAIL)....I did it on my by turn it 180 degree (half turn clock wire and it work) hope it help....cheer

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

[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

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.

This may or may not be your problem, but it may be worth a look...

I had a 260E that would stall while driving down the road, but would start back up and run fine. Sometimes it would stall and I would have to wait 15 minutes before it would start again...quite troublesome....

After checking and checking, one day I thought; "Could it be electrical?"

It was...the fuel pump electrical connector under the rear seat... When I took it apart, it was completely corroded. I removed it and soldered the wires (two pump system) and I never had the problem again....

Just a thought...

The Tenor Man

__________________
Currently Driving.....
1987 Mercedes Benz 300D Turbo - Daily Driver.
2004 Buick Rendezvous...Smaller than it looks!
2005 Mitsubishi Galant - Not bad for a tin box...Lousey Seats
Past Vehicles.....
1994 Dodge B-250 Van- GAS HOG..Succumbed to rust!
1989 Mercedes Benz 260E - Totaled but no one injured.
1977 Mercedes Benz 240D - Loved it, but SLOWWW! - Succumbed to RUST!
1976 Mercedes Benz 240D - Same as above! -
1975 Mercedes Benz 240D - Same as above!

The used potentiometer arrived Wednesday. However, the lower carbon track showed a lot of wear:



However, being an optimist, I installed it anyway, hoping for the best. I was able to start the car and get it adjusted to spec, but as expected it did not work well and it caused the check engine light to come on.

Yesterday I found a source for new potentiometers and have one on the way. The seller claims they are after-market and that he had them made, but claims to test them before shipping and he is offering a life-time warranty. I'll make a report once I have it installed.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire

at this stage the fuel pump relay and OVP are on the end of life with developing cold solder joints . Best to replace both of them or remove and clean pins and resolder the joints.
It solved my stalling problems when all else failed to rectify the problem.I hope this helps
mak
300se/ 90