Your symptoms are the same I had on my 190E. It was the Water Temp Sensor on mine that fixed the cold start issues. It tells the CIS-E the temp of the engine to fire the cold start valve as well as adjust the mixture via the EHA when the engine is warm. To have it run rich when cold and lean when too hot. This controls the EHA! It is a $40 part and is the two prong connector, the one with two individual plastic poles. Two seperate wires go to it.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

Morph,
If you had an intermittent problem, I could many hours of diagnosis, but you have a chronic problem that should have been diagnosed in 3 hours or less. MB has routine lists to follow in proper order to lead you to the problem component. Sounds like this shop is easter egging. Ask if they have a fuel pressure gauge with all the fittings to tie into your fuel distributer to measure fuel pressure with the engine running. Ask if they have a chart that shows the resistance reading of the temp sensor at different engine temps. Maybe you need to find a shop that is better equipped.

Peter

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Auto Zentral Ltd.

If you have the car with you and a Volt Ohm Meter you can check the sensor yourself.

The Chart of temps follows!

-20 15.7KOhm
-10 9.2KOhm
0 5.9KOhm
10 3.7KOhm
20 2.5KOhm
30 1.7KOhm
40 1.18KOhm
50 840Ohm
60 600Ohm
70 435Ohm
80 325Ohm
90 247Ohm

Now mine was reading lower resistances than it should of at said temps, causing the engine to be too lean at cold start and the Cold Start Injector to not fire. So I would have to try starting the engine twice basically and sometimes pump the gas to get it to run and warm up engough to stay running. Also had some issues with a warm start when shut off and then started less than an hour later. The temp sensor would read higher thus causing too lean a mixture. Also had ****ty gas mileage until fixed. I have also broken 2 of these sensor due to slip of the wrench type activities under the hood. Right now one post is broke off and a wire soldered to it to keep it connected, so I need to replace mine again as well. It is a fairly easy test. You just take the leads off and test the sensor. Then warm the car up to 80 degrees and turn off and test again. If your mixture is right you should be able to do this while the engine is running but may get a little bit of a stumble when you unplug it. If that is ok then I would say maybe the EHA is bad! But a 5-10 minute test of this sensor answers a lot of questions. Also have you tested your Cold Start Injector to make sure it works! Another easy one, you just remove it and put 12 V accross the connector momentarily and see if it clicks and fire. You can even re-attach the fuel line and check its spray pattern this way. Just don't light a match while doing it. And on a side note, if you are mechanically inclined, you should get the MB Maint CD as they are very helpfull in trouble shooting and testing everything. It has saved me from taking it to any shop. I have done all the work myself using info from this forum and 190Rev and that CD. Save a ton on labor costs and order all my parts online and save a ton there as well. I was quoted at $730 in labor to do my heater core from an MB Indy guy. Did it myself for free and an afternoon off. Took 5.5 hours and now I have heat again. So I saved myself $730 just because I am a cheap bastard. Good Luck and hopefully you get this resolved soon.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

Jamie,
I'm happy for you in the fact that you saved several hundred dollars by doing it yourself. I also repair things around my home to save money. I also applaud you for saying that you saved several hundred dollars rather than being ripped off for several hundred dollars. A professional shop would have charged you several hundred dollars, because of the expenses to keep the doors open to serve those who can't do it themselves. They are there to provide a service, and that costs money. It is no different than all the expenses it takes to keep a trauma center open for someone suffering a heart attack. What if all repair shops said that paying rent, insurance, permit costs, wages, taxes, refference library fees, $50,000 or more for BASIC tools, utilities, non chargeable supplies, etc. just wasn't worth it and shut down. Where would people take their cars? They just might as well abandon them by the roadside. So when a shop charges $80.00/hr, most of that money goes to the list above. I'm sure that no one reading this post goes to work every morning without any expectation of receiving a pay check for their efforts. I'm hoping to not hear from some smart ass retired people who do volunteer work. Jamie, at any rate the professional mechanics out there appreciate your attitude.

Thanks,
Peter

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Auto Zentral Ltd.

My family owned a Car Dealership for 75 years so I did not really need that lecture about the money side of doing Mechanical work. I was simply stating for me, the one who only spent $800 on the car for the purchase, it was not cost effective for me to spend $730 on labor costs for a heater core. And calculate that it took me 5.5 hours to do this job and it was my first time, and we get his labor rate of $132/hr. So you can see what my dilema was there. Also I have worked on cars for the better part of my adult life as well, so I am fine with doing so. Now working on cars is not for everyone, but chaning that little sensor takes all of ten minutes and if one who has even the slightest bit of mechanical knowledge can do it. But I really do not care what other people do with there money so it really does not matter. I was trying to have him diagnose something that I have seen in the past and have had many people thank me becuase it fixed there car as well. If his mechanic can't find something that is listed on the MB Maint CD in the list of tests to perfom than I would switch mechanics. Since it is right up there on the list as one of the first things to check. It is one thing to pay a good mechanic, it is another to waste your money.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

Sorry. Didn't intend to lecture anyone. I just saw an opportunity to support professional mechanics who are constantly bashed from all sides as rip off artists. I was not aware of the fact that your family had owned a dealership for 75 years.

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Auto Zentral Ltd.

Yeah, but I did not intend to say anyone was a rip-off artist, just that I did it for myself and saved money doing it that way. I have no problem taking the car to a mechanic if it is beyond my knowledge or my father-in-laws. He does his own work and has a nicely equiped garage. Although he is a Chevy fan, he still knows alot about engines. Sorry if I seemed to bash anyone, was really just trying to state some things can be done yourself. Also when done yourself it does give one the better understanding of how things work. Although I do not recommend the weak hearted or weak mechanically inclined to remove there dash board! It did not take long to do but was very frustrating when trying to put the heater box back in the car. They really do not give you much room in there.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I think our banter stems from the fact that you skimmed my post instead of reading it. Go back and reread and particularly my third sentence and my last sentence.

Peter

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Auto Zentral Ltd.

Oh I did kind sir. I was just trying to state that I was for Mechanics, just not for me in particular. That was all, I just did not want you to think I was one of those guys who disses the mechanics out there.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I'm glad we're back on the same page.

Peter

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Auto Zentral Ltd.

Group hug time.

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Norm in NJ
Next oil change at 230,000miles

Yep one big hug in this thread!

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I have been following this fix for a long time as many of the problems were familiar.

Last service I asked my specialist Benz repair shop to adjust the EHA as I had read. I believe they adjusted the screw a quarter turn or less and the results were negative.

Knowing I had directed them to make this adjustment I told them we had gone backwards in improving some of the starting and cold engine characteristics and the car went back in.

This time I was able to leave the car with them for a few days and they put the guages on and reset the upper and lower chamber pressure differential to .4bar as per spec. The intention was always to slightly richen the original setting to .45 bar.

Turns out that the original setting was way off. Perhaps done at a time before my ownership or perhaps it can change over time.

Either way the car is transformed.

It starts strong and positively with a noticebly consistent 3 or 4 rev crank time. It also is completely different off the line when cold. There is no flat spot or hesitation just smooth power.

For all you out there it is worth the specialist investment and time to get this adjustment professionally calibrated in older M103 engines.

89 300CE
152k kms

Bigblueone,
What did your mechanic to set the lower chamber pressure to .4 below primary pressure?

To the group,
I've been fooling around with an 89 300CE and have made some interesting observations. The o2 sensor output was about .8 volts at idle and went to about .1 at about 2000 rpms. I installed a used EHA and the o2 output liked to stay at about .8 idle and high speed. I hooked up the gas analyzer and it was < than 1 percent at idle and 2.5 at cruise. I installed another used EHA and o2 readings were the same, but cruise CO went to < than one percent. I don't know yet what all this means, but maybe the EHAs get unreliable with age and maybe someone has messed with the screw in back. I'll fool with this as I get more time and post back.

Peter

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Auto Zentral Ltd.

[QUOTE=autozen]Bigblueone,
What did your mechanic to set the lower chamber pressure to .4 below primary pressure?

Autozen
Not sure what you are asking here?

Because the intention of the first visit was to slightly richen the mixture and the results were so negative (i.e my previously strong cold start went AWOL) this time their goal was to confirm the factory spec setting of .4 bar.

They did this with pressure guages and the time to have the car through cold and warm starts although I am told that because of the very fine setting of .4 bar either you have to have highly calibrated guages or err slightly to just over .4 bar which they did.