Engine shaky after ignition but runs ok afterwards for w114 250CE

Hi
I have now encountered a problem where my engine is shaky and seems to almost want to shut down after ignition. But after leaving it on for like 10-15 minutes, the engine is smoother and then there is no problem. The engine is less shaky and can say there is no prolem. Can you suggest where I should start investigating in my M114.980 engine for the Mercedes Benz w114 250CE? I have cleaned the fuel injectors already and changed a new pressure regulator.

Cheers
Archie

Achab90 wrote: ... my engine is shaky and seems to almost want to shut down after ignition. ...

Hi, I interprete what you wrote: After cold start (?)

Did you check tthe whole ignition? This is the first thing to do.
The early CE250 has a 'traditional' ignition with points and no electronic 'amplifier'. Therefor the points trend to have wear.

Second thing: The auxiliary air valve (AAV) gives additional air when the engine is cold. AAV not working means no extra air and low revs.

Check this. Does the AAV open < a liitle bit> when the engine is cold?

Regards
Norbert

...sorry, that´s not correct, Norbert only the early 250 CE have the coil ignition, the later ones have also the transistorised ignition !

Greets Christian

Thank you, Christian.
I have seen early CE250 ones only.
Correct it in my posting.
Regards
Norbert

Hi Archie,

several things can happen in a failing cold start

• Auxiliary air valve could hang and not open. This is what increases rpm during warm run. On your car you can remove the small filter on AAV and check whether engine sucks in air there.
• A ignition distributor can also hang. Verify ignition timing on ice cold engine. Both in dle and in 1500 rpm if you can. Also verify vacuum retard.
• Verify resistance of engine temp sensor on ECU connector when engine is cold and when it is warm
• Verify that cold start valve injects while cranking engine.

Where did you get a new pressure regulator? And how is fuel pressure right now?

Hi
Thank you again for your reply.
Silly question but I think it's an appropriate time to ask. I am currently living in Thailand which is a tropical country with weather at around 30-40 degrees Celsius. I never paid much attention to the cold start valve because I had figured it was for Western countries with a lower temperature, especially during winter. So, is the cold start valve still necessary for me here?

I will have a look at all your suggestions and see the results.

For the new pressure regulator, it was very fortunate that I found one, although it cost around 240 euros. For the fuel pressure, I have not had the chance to change to the Pierburg you had suggested yet. Shipping has been delayed these past few months so have not received the part yet.