250ce running rich

First off all, hi everyone and thanks for the add!
After bigger service made on the engine and car itself and checking a lot of components it still have following issues:

- Car is running rich, spark plugs gets black and clogged after a while, has big fuel consumption
-with cold start, engine has maybe 400-500rpm, and it is almost dying, when engine is hot rpm is 1200-1300rpm, while standing i P.
- some sort of lack of power.
-screw on the intake manifold for adjusting rpm does not seem to work
- with disconnected cold start valve car seems to run little bit better, so it is off for now
- engine runs rough and shaking

I'm writing down following things which I have checked in last few days:
+ Fuel pressure, exactly 2 bar pressure
+ MAP sensor(type 3 with black cover on), pumped 0.5 bar vacuum, it is standing there, no leakages
+ Ignition, been replaced to electronically, ignition point, 4* BTDC
+ AAV seems to work, it sucks air in when cold, and stops afterwards, but maybe not completely stops
+ Installed new timing chain, because of excessive stretch (was ~8 degrees off between camshaft and crankshaft), restored engine head, all new seals, adjusted valves.
I drove 45km another day, it runs but engine doesn't feels very happy

Any ideas where I should look next?

Hi unknown user,

it would be noce if u could introduce yourself shortly and also sign with your first name. We like to greet each other by their names here.

Regarding your problems:

+ MAP sensor(type 3 with black cover on), pumped 0.5 bar vacuum, it is standing there, no leakages
BINGO! A 250 CE never has a type 3 MAP sensor. It always has a type 2 MAP sensor. You have the wrong MAP sensor, no wonder your mixture is wrong.

+ Ignition, been replaced to electronically, ignition point, 4* BTDC
Why would one do that. All but very early 250 CEs have transitorized ignition. And what does 4* BTDC stand for?

I just wrote a long answer, but it didnt seem to appear here.. I will do it later again, then. I used quick reply button.
Regards
Lauris

Volker
4* BTDC = bevor top dead Center. 4 grad früh Zündung.
Rudiger

Long story short. I live in Norway, near Oslo and working at the Nissan/Subaru dealer as a car body worker, currently, for last year I am working at Tesla department as car body worker/ technician. Educated as mechanic as well. Passionate about Mercedes, I have had few before too.

Ok, back to the case.
The car is registrated in mid 72', but is a pre-facelift model, I believe it could be few years older. Car was designated for US market, but never were exported and was sold new in Norway. (I have orange side markers on rear on front fenders, on the steering column I have also riveted plate where gear shift mechanism should be, but have regular 4 gear automatic instead). Those who knows, asks if ti is a US import car. Could it be at US market 250ce cars has type 3 MAP sensors or it is only type 2? If so, where could I find one?

Ignition, well, I had hard times finding right parts for points, and have at least 2-3 wrong points, even if I ordered them from different places after car spec., I always got wrong ones, the same with ignition rotors. I ordered one for 114.980 engine which I have and still got wrong. (Most parts I am checking from w113 and w108/w109, like fuel filter fits from w108, but not the one which should be for mine.)
I got huge improvments how the engine works, when installed electronical ignition, so I will keep it until all the systems works properly, because ignition seems to be very stable now.
And 4* BTDC stands for - ignition point is set to 4 degrees before top dead center, like Rudiger allready mentioned it. I have transitorized ignition system, so I did included it when wiring up this electr. ignition.

Any other ideas or it is just to find type 2 MAP sensor in the beggining?

Regards
Lauris

Hi Lauris,

all 250 CE have type 2 MAP sensors. You will find component list in Appendix A . A type 3 is definitely wrong. I am pretty sure that your 250CE one day had a broken diaphragm and some smart ass replaced it by a 0280100111 for 280 engines. Buying a type 2 MAP sensor is a gamble as people mainly sell them when they are leaking. I will check whether I have suitable for you in my stock. I should have, but I have to search.

Also all ignition points including transistorized ignition module are in that Appendix A. A contact from Bosch with ignition module will not wear any more. I would BTW have understood 4° BTDC but you wrote 4* which I read as 4 times and got confused. I recommend that you also check what happened to your ignition module 0 227 051 015. Sounds like it also vanished.