E280 1995 W124 Uneven idle

My E280 has uneven idle since a few days ago. Sometimes the engine stops. The idle is OK when the engine is cold. When the engine gets warm and it tries to settle down on a low idle the idle goes up and down and black smoke comes from the exhaust pipe. Does anybody know what could be wrong?.

Fuel mixture is too rich...I would suspect your temperature sensor for the fuel injection system dies and registered improper temperature. Otherwise, it would be better to have a mechanic with true MB diagnostic scanner to test your car... not many have them.

Black smoke in the exhaust is a sign that the engine is being over fueled given the quantity of air being allowed into the engine - normal being about 14.7:1 air to fuel.
This could be from a number of possible causes:
A dirty or stuck fuel injector. Bad O2 sensor. Bad temperature sensor (always indicating a cold engine).
The engine's computer stores fault codes; your shop has an electronic code reader that may find a diagnostic code that pin points the problem.

Your car has owner access code retrieval under the hood LED/SW with Flash code system.. Hold button for 2 secs, release , codes will come back as led flash/blinks in numerical sequence. Look for 16 pin diagnostic socket in front of battery.... Black removable lid Are you in Europe ???

On 02 Oct 2004 20:59:16 GMT, snipped-for-privacy@aol.com (AJDalton7) wrote:
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I am in Europe. I dont have the button and the LED.

Yeah, Euro no got ..
Do you have the 16 pin socket?

On 02 Oct 2004 21:19:17 GMT, snipped-for-privacy@aol.com (AJDalton7) wrote:
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I have the 16 pin socket. I know i need some code reader to read out the error codes.
How do i know if i have any error codes to read?.

I have a little tool design you can make for about $5 [US] email if you want a jpg of the parts/schematic.. it is in pictoral form for those not familiar w/schematic symbols....
This will get you the stored codes and you can list them.
Also, the common faults in line with your complaints are the 3 plug to coil connectors under each coil.. They are cheap and we have learned to change them whever changing plugs [Have found Beru best bet] The other check you should make is the Over Voltage relay .. it is behind the panel near battery..aluminum rectangular can w/fuse on top If it has the original part# 000 540-52-45, change it to 000 540 67 45..regardless.