Staling when starting if engine is cold

[timewind]

Hi all

Since 2 days I have the problem that the engine is stalling if cold. The revs are going up to about 600 then dropping to 200 hundred and then the engine stalls. After 2 or 3 tries the engine starts but the revs are still unstable and i need to accelerate to keep the revs up until the engine is warmer.
No problems with starting if the engine is warm (idle at 800 straight ).


Another symptom is that the engine is running very rough if cold and sounds somehow grinding.

I have the thought it could be the stepper or maybe the spark plugs?

But before I spend my weekend searching on the wrong thing (I'm not much of an engineer ) what do you think?

Thanks for your help!

[shpub]

Clean the steeper or even the stepper motor first and see what happens.