Idle speed adjusting Bosch CI K-jetronic

I own a 900 88 B201 H, With Bosch CI K-jetronic with catalytic converter. So I want to know how to fix the proper idle rpm, right now is at 1200 and should be only 850rpm. I dont know if the ECU or either the modulation valve adjust it automatically, if so How can I adjust the speed to 850rpm.

I own a 900 B201 H Bosch CI K- Jetronic catalizator.
At idle I got 1200rpm, I understand that this car has automatic idle speed regulation,
Which problem can I have?

Regards