strakonice

when engine is started and is cold, first is O.K when cold start valve is on. After when engine is sort off warm up and rpm drops as enrichment shuts off engine check light come on and is on for 10 + seconds while engine rpms goes up after dropping down like engine management system trying to enrich mixture. When warmed up enough engines light goes off it self and never come back. Rpm showing in that period between 950 to 1,000 and when car is warm it sits on about 900 rpm. There are no error codes when scanning by fuse inserted to the fuel pump relay. Car is 1988 Audi 90 manual 5cyl no Quatro.

Thanks for inputs,
Paul