I have the same problem as everyone else, My 1989 109E 2.6 engin# 103.942, chassis# 201.029 with CIS, stalls like the key was shut off when it is over 85 deg. C. but starts rite back up. Also it idles low, 500rpms, as soon as it reaches 85deg all the time. these two problems may or may not be related, I don't know. I see you all talking about this but no complete conclusions. I believe it's a heat soke issue, but what part? It has to be electrical.
I've checked fuel flow and pressure. I changed the 4wire temp sensor and the OVP relay.I even added a 1/0 ground wire from the block to the battery.
First question: what tells the engine computer how fast the engine is spinning? The crank sensor?, the mas airflow?, the manifold absoulute pressure sensor?, just the RPM sensor or all in conjunction. What would heat up the most?
Something is telling the computer the engine is spinning faster than it really is and is closing the idle air control motor, I cleaned the IAC with Brake Cleaner, wasn't really dirty. I tried to raise the base idle with the throttle plate adjustment screw under the MAS and the computer put it back to 500rpm, only the TPS advanced base timming, so I put base idle back. When engine cools back to 85 deg. C the stalling stops and idle goes back to 750rpm. I pulled out the timing resistor and this did give me 25 more rpm and alittle more hp.
I know that the Idle control valve is working and the computer is controling idle because the computer raises idle back to 500 when I turn the A/C on.
Could it be going into limp in mode after it heats up? I can drive the car all day on a foggy day and if it never get above 85deg it does not stall. If I disconnect the micro switch on the throttle linkage it idles back up.What does that micro switch tell the computer?
This only happens when its hot, so my next step is to heat up each part with a heat gun until it stalls.
It's all guess work for me, anyone got any ideas?

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Spang

What are the rpm hot and cold?

Fault OVP Ussualy slow RPM when cold and fast when hot.
Or it could be a fuel pump relay?

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1985 190E - Gone
1989 230E - Gone
1995 C200 - Gone
1993 280E 120000KM - Built like a brick, the best one yet

Hello members , My car have 180K miles on the clock.Recently Cruise control did not worked ans ABS light appear on Instrument panel so I decide to tacke down some Electronic components behind a battery compartment.There are 4 main devices are:ABS;ECU;MAS and OVP relay.In number post on the Web site I've read and it mention about a broken circuitry inside the ECU unit or similar other device . I did investigate by open all to look inside entire the printed circiut board with magnified class( make sure I grounded myself and DON'T touch any I/C or related electro components cause your body generate elctricity could damage it) .Well nothing seem to be problems then I put them back and start the car.It just start but not run normal like it used to be. What did I do wrong in here? Thanks and appreciate for any of your inputs

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Do'nt worry and be happy !

Replying to an existing thread and effectively starting another topic is referred to as "highjacking the thread" It is bad forum etiquette, and virtually guarantees you'll get no responses to your question. It also hampers the original poster's quest for their answer.

Suggest you repost your question in a new thread and allow the original poster to retain the continuity of their own topic.

To Wbrian and Spang4190E. Sorry for that post that I'm not intention to mean to insult anyone on this board.Please accept my apolozige.Thought IMHO I just post what did it happen to me when I'm trying to fix my car and these symtoms occur to mine.Really I would like someone to show me in details how to post correctly on this web site.Thanks a lots.

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Do'nt worry and be happy !

benz4le.
To start a new thread ; ShopForum > Technical Information and Support > Choose the section you want > Top of page - New Thread .

Benz4le, it's cool no hard feelings.
Also I think I came upon something, when I unplug the thing called the EHA valve the car runs great, idle is back to 650 in gear and smooth. But it is hard to start and ck eng lite is on as expected. Question?What does the EHA valve control and what controles it?

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Spang