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Greetings W123 Technicians.
My W123 2.8 Coupe, K-Jetronic Injection. 1985.

The engine starts immediatly on cold start, but the cold start idling speed is too low ( 550-600 rpm) and the engine stalls. It used to be about 850. How can this be adjusted, or does something need to be cleaned/changed. Once warm, the engine runs at around 700 rpm on idle.
Chassis number is WDB1230531A256819. Thank you in advance.
Engelse Hans.

Hans, see the picture



This is a M102.980 engine, but the K-jetronic is basically the same as with the M110.
Two subsystems control the mixture in warm-up phase:

[*]The warm-up regulator ('Warmloopregelaar') does enrich the mixture by lowering the control pressure. Inside the regulator is a bimetallic spring that could be broken. You can check the warm-up regulator by measuring the pressure at both connected fuel lines in warm-up phase. If you don't have the equipment, disconnect the fuel lines and try to blow air in. If the regulator is working basically the air should come out of the other connector

[*]Secondly look at the auxiliary air valve. In warm-up phase this valve is open for extra air in order to rise the rpm. See the picture, part no.3. Again this is the situation in a M102.980, but for the idea it should do



Inside there is also a bimetallic spring that could be broken, or airflow to the air valve could be blocked

Caspar<br><br>Post edited by: Trouwkoets, at: 2008/02/13 14:20

Your idle speed should be around 800 ± 50 rpm so it is definitely to low. You can adjust this with the screw (10) on the picture which is located near your ignition.
If your engine running smoothly I would not trying to fix anything, but looking if rising your idle speed solve your problem without causing more unwanted effects.

Regards,

Jan

The warm-up regulator on a 280 is located near the oil filter

Regards,

Jan

Thank you all for your help!

I will attend to this problem today

Hans.